Please refer to the errata for this document, which may include some normative corrections.
See also translations.
This document is also available in these non-normative formats: XML and Change markings relative to first edition.
Copyright © 2010 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark and document use rules apply.
This document defines serialization of an instance of the data model as defined in [XQuery 1.0 and XPath 2.0 Data Model] into a sequence of octets. Serialization is designed to be a component that can be used by other specifications such as [XSL Transformations (XSLT) Version 2.0] or [XQuery 1.0: An XML Query Language].
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
This is one document in a set of eight documents that are being progressed to Edited Recommendation together (XPath 2.0, XQuery 1.0, XQueryX 1.0, XSLT 2.0, Data Model (XDM), Functions and Operators, Formal Semantics, Serialization).
This document, published on 14 December 2010, is an Edited Recommendation of the W3C. This second edition is not a new version of this specification; its purpose is to clarify a number of issues that have become apparent since the first edition was published. All of these clarifications (excepting trivial editorial fixes) have been published in a separate errata document, and published in a Proposed Edited Recommendation in April, 2009. The changes are summarized in an appendix.
This document has been jointly developed by the W3C XML Query Working Group and the W3C XSL Working Group, each of which is part of the XML Activity.
This document has been reviewed by W3C Members, by software developers, and by other W3C groups and interested parties, and is endorsed by the Director as a W3C Recommendation. It is a stable document and may be used as reference material or cited from another document. W3C's role in making the Recommendation is to draw attention to the specification and to promote its widespread deployment. This enhances the functionality and interoperability of the Web.
This document incorporates changes made against the Recommendation of 23 January 2007 that resolve all errata known at the date of publication. A list of the errata that have been applied, with links to the Bugzilla database, is provided in E Changes since the First Edition. The version of this document with change highlighting indicates where the textual changes have been made, and cross-references each textual change to the erratum where it originated. This document supersedes the first edition.
This specification is designed to be referred to normatively from other specifications defining a host language for it; it is not intended to be implemented outside a host language. The implementability of this specification has been tested in the context of its normative inclusion in host languages defined by the XQuery 1.0 and XSLT 2.0 specifications; see the XQuery 1.0 implementation report and the XSLT 2.0 implementation report (member-only) for details.
Please report errors in and submit comments on this document using W3C's public Bugzilla system (instructions can be found at http://www.w3.org/XML/2005/04/qt-bugzilla). If access to that system is not feasible, you may send your comments to the W3C XSLT/XPath/XQuery public comments mailing list<EMAIL_ADDRESS>It will be very helpful if you include the string "[SER]" in the subject line of your report, whether made in Bugzilla or in email. Each Bugzilla entry and email message should contain only one error report. Archives of the comments and responses are available at http://lists.w3.org/Archives/Public/public-qt-comments/.
This document was produced by groups operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the XML Query Working Group and also maintains a public list of any patent disclosures made in connection with the deliverables of the XSL Working Group; those pages also include instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.
1 Introduction
1.1 Terminology
2 Sequence Normalization
3 Serialization Parameters
4 Phases of Serialization
5 XML Output Method
5.1 The Influence of
Serialization Parameters upon the XML Output Method
5.1.1 XML Output Method: the version Parameter
5.1.2 XML Output Method: the encoding Parameter
5.1.3 XML Output Method: the indent Parameter
5.1.4 XML Output Method: the
cdata-section-elements Parameter
5.1.5 XML Output Method: the
omit-xml-declaration and standalone Parameters
5.1.6 XML Output Method: the doctype-system and
doctype-public Parameters
5.1.7 XML Output Method: the undeclare-prefixes
Parameter
5.1.8 XML Output Method: the normalization-form
Parameter
5.1.9 XML Output Method: the media-type
Parameter
5.1.10 XML Output Method: the use-character-maps
Parameter
5.1.11 XML Output Method: the byte-order-mark
Parameter
5.1.12 XML Output Method: the
escape-uri-attributes Parameter
5.1.13 XML Output Method: the
include-content-type Parameter
6 XHTML Output Method
6.1 The Influence
of Serialization Parameters upon the XHTML Output Method
6.1.1 XHTML Output Method: the version
Parameter
6.1.2 XHTML Output Method: the encoding
Parameter
6.1.3 XHTML Output Method: the indent Parameter
6.1.4 XHTML Output Method: the
cdata-section-elements Parameter
6.1.5 XHTML Output Method: the
omit-xml-declaration and standalone Parameters
6.1.6 XHTML Output Method: the doctype-system and
doctype-public Parameters
6.1.7 XHTML Output Method: the
undeclare-prefixes Parameter
6.1.8 XHTML Output Method: the
normalization-form Parameter
6.1.9 XHTML Output Method: the media-type
Parameter
6.1.10 XHTML Output Method: the
use-character-maps Parameter
6.1.11 XHTML Output Method: the byte-order-mark
Parameter
6.1.12 XHTML Output Method: the
escape-uri-attributes Parameter
6.1.13 XHTML Output Method: the
include-content-type Parameter
7 HTML Output Method
7.1 Markup for
Elements
7.2 Writing
Attributes
7.3 Writing
Character Data
7.4 The Influence of
Serialization Parameters upon the HTML Output Method
7.4.1 HTML Output Method: the version Parameter
7.4.2 HTML Output Method: the encoding
Parameter
7.4.3 HTML Output Method: the indent Parameter
7.4.4 HTML Output Method: the
cdata-section-elements Parameter
7.4.5 HTML Output Method: the
omit-xml-declaration and standalone Parameters
7.4.6 HTML Output Method: the doctype-system and
doctype-public Parameters
7.4.7 HTML Output Method: the
undeclare-prefixes Parameter
7.4.8 HTML Output Method: the
normalization-form Parameter
7.4.9 HTML Output Method: the media-type
Parameter
7.4.10 HTML Output Method: the
use-character-maps Parameter
7.4.11 HTML Output Method: the byte-order-mark
Parameter
7.4.12 HTML Output Method: the
escape-uri-attributes Parameter
7.4.13 HTML Output Method: the
include-content-type Parameter
8 Text Output Method
8.1 The Influence of
Serialization Parameters upon the Text Output Method
8.1.1 Text Output Method: the version Parameter
8.1.2 Text Output Method: the encoding
Parameter
8.1.3 Text Output Method: the indent Parameter
8.1.4 Text Output Method: the
cdata-section-elements Parameter
8.1.5 Text Output Method: the
omit-xml-declaration and standalone Parameters
8.1.6 Text Output Method: the doctype-system and
doctype-public Parameters
8.1.7 Text Output Method: the
undeclare-prefixes Parameter
8.1.8 Text Output Method: the
normalization-form Parameter
8.1.9 Text Output Method: the media-type
Parameter
8.1.10 Text Output Method: the
use-character-maps Parameter
8.1.11 Text Output Method: the byte-order-mark
Parameter
8.1.12 Text Output Method: the
escape-uri-attributes Parameter
8.1.13 Text Output Method: the
include-content-type Parameter
9 Character Maps
10 Conformance
A References
A.1 Normative References
A.2 Informative References
B Summary of Error Conditions
C List of URI
Attributes
D Checklist of
Implementation-Defined Features (Non-Normative)
E Changes since the First
Edition (Non-Normative)
This document defines serialization of the W3C XQuery 1.0 and XPath 2.0 Data Model (XDM), which is the data model of at least [XML Path Language (XPath) 2.0], [XSL Transformations (XSLT) Version 2.0], and [XQuery 1.0: An XML Query Language], and any other specifications that reference it.
Serialization is the process of converting an instance of the [XQuery 1.0 and XPath 2.0 Data Model] into a sequence of octets. Serialization is well-defined for most data model instances.
In this specification, where they appear in upper case, the words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", "MAY", "REQUIRED", and "RECOMMENDED" are to be interpreted as described in [RFC2119].
[Definition: As is indicated in 10 Conformance, conformance criteria for serialization are determined by other specifications that refer to this specification. A serializer is software that implements some or all of the requirements of this specification in accordance with such conformance criteria.] A serializer is not REQUIRED to directly provide a programming interface that permits a user to set serialization parameters or to provide an input sequence for serialization. In this document, material labeled as "Note" and examples are provided for explanatory purposes and are not normative.
Certain aspects of serialization are described in this specification as implementation-defined or implementation-dependent.
[Definition: Implementation-defined indicates an aspect that MAY differ between serializers, but whose actual behavior MUST be specified either by another specification that sets conformance criteria for serialization (see 10 Conformance) or in documentation that accompanies the serializer.]
[Definition: Implementation-dependent indicates an aspect that MAY differ between serializers, and whose actual behavior is not REQUIRED to be specified either by another specification that sets conformance criteria for serialization (see 10 Conformance) or in documentation that accompanies the serializer.]
[Definition: In some instances, the sequence that is input to serialization cannot be successfully converted into a sequence of octets given the set of serialization parameter (3 Serialization Parameters) values specified. A serialization error is said to occur in such an instance.] In some cases, a serializer is REQUIRED to signal such an error. What it means to signal a serialization error is determined by the relevant conformance criteria (10 Conformance) to which the serializer conforms. In other cases, there is an implementation-defined choice between signaling a serialization error and performing a recovery action. Such a recovery action will allow a serializer to produce a sequence of octets that might not fully reflect the usual requirements of the parameter settings that are in effect.
Many terms used in this document are defined in the XPath specification [XML Path Language (XPath) 2.0] or the Data Model specification [XQuery 1.0 and XPath 2.0 Data Model]. Particular attention is drawn to the following:
[Definition: The term atomization is defined in Section 2.4.2 AtomizationXP. It is a process that takes as input a sequence of nodes and atomic valuesXP, and returns a sequence of atomic valuesXP, in which the nodes are replaced by their typed valuesXP as defined in [XQuery 1.0 and XPath 2.0 Data Model].]
[Definition: The term Node is defined as part of Section 6 NodesDM. There are seven kinds of nodes in the data model: document, element, attribute, text, namespace, processing instruction, and comment.]
[Definition: The term sequence is defined in Section 2 BasicsXP. A sequence is an ordered collection of zero or more items.]
[Definition: The term string value is defined in Section 5.13 string-value AccessorDM. Every node has a string value. For example, the string value of an element is the concatenation of the string values of all its descendant text nodes.]
[Definition: The term expanded QName is defined in Section 2 BasicsXP. An expanded QName consists of an optional namespace URI and a local name. An expanded QName also retains its original namespace prefix (if any), to facilitate casting the expanded QName into a string.]
[Definition: An element or attribute that is in no namespace, or an expanded-QName whose namespace part is an empty sequence, is referred to as having a null namespace URI].
[Definition: An element or attribute that does not have a null namespace URI, is referred to as having a non-null namespace URI].
An instance of the data model that is input to the serialization process is a sequence. Prior to serializing a sequence using any of the output methods whose behavior is specified by this document (3 Serialization Parameters), the serializer MUST first compute a normalized sequence for serialization; it is the normalized sequence that is actually serialized. [Definition: The purpose of sequence normalization is to create a sequence that can be serialized as a well-formed XML document or external general parsed entity, that also reflects the content of the input sequence to the extent possible.] [Definition: The result of the sequence normalization process is a result tree.]
The normalized sequence for serialization is constructed by applying all of the following rules in order, with the initial sequence being input to the first step, and the sequence that results from any step being used as input to the subsequent step. For any implementation-defined output method, it is implementation-defined whether this sequence normalization process takes place.
Where the process of converting the input sequence to a
normalized sequence indicates that a value MUST be
cast to xs:string
, that operation is defined in
Section
17.1.2 Casting to xs:string and
xs:untypedAtomicFO of [XQuery 1.0 and XPath 2.0 Functions and
Operators]. Where a step in the sequence normalization
process indicates that a node should be copied, the copy is
performed in the same way as an XSLT xsl:copy-of
instruction that has a validation
attribute whose
value is preserve
and has a select
attribute whose effective value is the node, as described in
Section 11.9.2 Deep
CopyXT of [XSL
Transformations (XSLT) Version 2.0], or equivalently in the
same way as an XQuery content expression as described in Step 1e of
Section <IP_ADDRESS>
ContentXQ of [XQuery 1.0: An XML Query Language], where the
construction mode is preserve
. The steps in
computing the normalized sequence are:
If the sequence that is input to serialization is empty, create a sequence S1 that consists of a zero-length string. Otherwise, copy each item in the sequence that is input to serialization to create the new sequence S1.
For each item in S1, if the item is atomic,
obtain the lexical representation of the item by casting it to an
xs:string
and copy the string representation to the
new sequence; otherwise, copy the item, which will be a node, to the new sequence. The new
sequence is S2.
For each subsequence of adjacent strings in S2, copy a single string to the new sequence equal to the values of the strings in the subsequence concatenated in order, each separated by a single space. Copy all other items to the new sequence. The new sequence is S3.
For each item in S3, if the item is a string, create a text node in the new sequence whose string value is equal to the string; otherwise, copy the item to the new sequence. The new sequence is S4.
For each item in S4, if the item is a document node, copy its children to the new sequence; otherwise, copy the item to the new sequence. The new sequence is S5.
For each subsequence of adjacent text nodes in S5, copy a single text node to the new sequence equal to the values of the text nodes in the subsequence concatenated in order. Any text nodes with values of zero length are dropped. Copy all other items to the new sequence. The new sequence is S6.
It is a serialization error [err:SENR0001] if an item in S6 is an attribute node or a namespace node. Otherwise, construct a new sequence, S7, that consists of a single document node and copy all the items in the sequence, which are all nodes, as children of that document node.
S7 is the normalized sequence.
The result tree rooted at the document node that is created by the final step of this sequence normalization process is the instance of the data model to which the rules of the appropriate output method are applied. If the sequence normalization process results in a serialization error, the serializer MUST signal the error.
Note: The sequence normalization process for a sequence
$seq
is equivalent to constructing a document node using the XSLT instruction:<xsl:document> <xsl:copy-of select="$seq" validation="preserve"/> </xsl:document>or the XQuery expression:
declare construction preserve; document { for $s in $seq return if ($s instance of document-node()) then $s/child::node() else $s }This process results in a serialization error [err:SENR0001] if sequences contain parentless attribute and/or namespace nodes.
There are a number of parameters that influence how serialization is performed. Host languages MAY allow users to specify any or all of these parameters, but they are not REQUIRED to be able to do so. However, the host language specification MUST specify how the value of all applicable parameters is to be determined.
It is a serialization error [err:SEPM0016] if a parameter value is invalid for the given parameter. It is the responsibility of the host language to specify how invalid values should be handled at the level of that language.
The following serialization parameters are defined:
| Serialization parameter name | Permitted values for parameter |
|---|---|
byte-order-mark |
One of the enumerated values
yes or no . This parameter indicates
whether the serialized sequence of octets is to be preceded by a
Byte Order Mark. (See Section 5.1 of [Unicode Encoding].) The actual octet order
used is implementation-dependent. If the encoding defines no
Byte Order Mark, or if the Byte Order Mark is prohibited for the
specific Unicode encoding or implementation environment, then this
parameter is ignored. |
cdata-section-elements |
A list of expanded QNames, possibly empty. |
doctype-public |
A string of PubidCharXML characters. This parameter may be absent. |
doctype-system |
A string of Unicode characters that does not include both an apostrophe (#x27) and a quotation mark (#x22) character. This parameter may be absent. |
encoding |
A string of Unicode characters in the
range #x21 to #x7E (that is, printable ASCII characters); the value
SHOULD be a charset registered with the Internet
Assigned Numbers Authority [IANA], [RFC2278] or begin with the characters
x- or X- . |
escape-uri-attributes |
One of the enumerated values
yes or no . |
include-content-type |
One of the enumerated values
yes or no . |
indent |
One of the enumerated values
yes or no . |
media-type |
A string of Unicode characters
specifying the media type (MIME content type) [RFC2046]; the charset parameter of the media type
MUST NOT be specified explicitly in the value of
the media-type parameter. If the destination of the
serialized output is annotated with a media type, this parameter
MAY be used to provide such an annotation. For
example, it MAY be used to set the media type in
an HTTP header. |
method |
An expanded QName with a null namespace
URI, and the local part of the name equal to one of
xml , xhtml , html or
text , or having a non-null namespace URI. If the
namespace URI is non-null, the parameter specifies an implementation-defined
output method. |
normalization-form |
One of the enumerated values
NFC , NFD , NFKC ,
NFKD , fully-normalized , none
or an implementation-defined value. |
omit-xml-declaration |
One of the enumerated values
yes or no . |
standalone |
One of the enumerated values
yes , no or omit . |
undeclare-prefixes |
One of the enumerated values
yes or no . |
use-character-maps |
A list of pairs, possibly empty, with each pair consisting of a single Unicode character and a string of Unicode characters. |
version |
A string of Unicode characters. |
The value of the method
parameter is an expanded QName. If
the value has a null namespace URI, then the local name
identifies a method specified in this document and
MUST be one of xml
,
html
, xhtml
, or text
; in
this case, the output method specified MUST be
used for serializing. If the namespace URI is non-null, then it
identifies an implementation-defined output method; the behavior in
this case is not specified by this document.
In those cases where they have no important effect on the content of the serialized result, details of the output methods defined by this specification are left unspecified and are regarded as implementation-dependent. Whether a serializer uses apostrophes or quotation marks to delimit attribute values in the XML output method is an example of such a detail.
The detailed semantics of each parameter will be described separately for each output method for which it is applicable. If the semantics of a parameter are not described for an output method, then it is not applicable to that output method.
Implementations MAY define additional
serialization parameters, and MAY allow users to
do so. For this purpose, the name of a serialization parameter is
considered to be a QName; the parameters listed above are QNames in
no namespace, while any additional serialization parameters must
have names that are namespace-qualified. If the serialization
method is one of the four methods xml
,
html
, xhtml
, or text
, then
the additional serialization parameters MAY affect
the output of the serializer to the extent (but only to the extent)
that this specification leaves the output implementation-defined
or implementation-dependent. For example, such
parameters might control whether namespace declarations on an
element are written before or after the attributes of the element,
or they might define the number of space or tab characters to be
inserted when the indent
parameter is set to
yes
; but they could not instruct the serializer to
suppress the error that occurs when the HTML output method
encounters illegal characters (see error [err:SERE0014]).
Serialization comprises five phases of processing (preceded optionally by the sequence normalization process described in 2 Sequence Normalization).
For an implementation-defined output method, any of these phases MAY be skipped or MAY be performed in a different order than is specified here. For the output methods defined in this specification, these phases are carried out sequentially as follows:
A meta
element is added to the normalized sequence
along with discarding an existing meta
element, as
controlled by the include-content-type
parameter for
the XHTML and HTML output methods.
Markup generation produces the character representation of those parts of the serialized result that describe the structure of the normalized sequence. In the cases of the XML, HTML and XHTML output methods, this phase produces the character representations of the following:
the document type declaration;
start tags and end tags (except for attribute values, whose representation is produced by the character expansion phase);
processing instructions; and
comments.
In the cases of the XML and XHTML output methods, this phase also produces the following:
the XML or text declaration; and
empty element tags (except for the attribute values);
In the case of the text output method, this phase replaces the single document node produced by sequence normalization with a new document node that has exactly one child, which is a text node. The string value of the new text node is the string value of the document node that was produced by sequence normalization.
Character expansion is concerned with the representation of characters appearing in text and attribute nodes in the normalized sequence. For each text and attribute node, the following rules are applied in sequence.
If the node is an attribute that is a URI attribute
value and the escape-uri-attributes
parameter is
set to require escaping of URI attributes, apply URI escaping as defined
below, and skip rules b-e. Otherwise, continue with rule b.
[Definition: URI escaping consists of the following three steps applied in sequence to the content of URI attribute values:]
normalize to NFC using the method defined in Section 7.4.6 fn:normalize-unicodeFO
percent-encode any special characters in the URI using the method defined in Section 7.4.12 fn:escape-html-uriFO
escape according to HTML rules any characters (such as
<
and &
) where HTML requires
escaping, and any characters that cannot be represented in the
selected encoding. For example, replace <
with
<
. (See also section 7.3 Writing Character Data)
[Definition: The values of attributes
listed in C List of URI
Attributes are URI attribute values. Attributes are
not considered to be URI attributes simply because they are
namespace declaration attributes or have the type annotation
xs:anyURI
.]
If the node is a text node whose parent element is selected by
the rules of the cdata-section-elements
parameter for
the applicable output method, create CDATA sections as described
below, and skip rules c-e. Otherwise, continue with rule c.
Apply the following two processes in sequence to create CDATA sections
Unicode Normalization if requested by
the normalization-form
parameter.
apply changes as detailed in the description of the
cdata-section-elements
parameter for the applicable
output method.
Apply character mapping as determined by the
use-character-maps
parameter for the applicable output
method. For characters that were substituted by this process, skip
rules d and e. For the remaining characters that were not modified
by character mapping, continue with rule d.
Apply Unicode Normalization if requested by
the normalization-form
parameter.
[Definition: Unicode Normalization is the process of removing alternate representations of equivalent sequences from textual data, to convert the data into a form that can be binary-compared for equivalence, as specified in [UAX #15: Unicode Normalization Forms]. For specific recommendations for character normalization on the World Wide Web, see [Character Model for the World Wide Web 1.0: Normalization].]
The meanings associated with the possible values of the
normalization-form
parameter are defined in section
5.1.8 XML Output Method: the
normalization-form Parameter.
Continue with step e.
Escape according to XML or HTML rules, as determined by the
applicable output method, any characters (such as <
and &
) where XML or HTML requires escaping, and
any characters that cannot be represented in the selected encoding.
For example, replace <
with <
.
(See also section 7.3 Writing Character
Data). For characters such as >
where XML
defines a built-in entity but does not require its use in all
circumstances, it is implementation-dependent whether the character
is escaped.
Indentation, as controlled by the indent
parameter, MAY add or remove whitespace according to the rules
defined by the applicable output method.
Encoding, as controlled by the encoding
parameter, converts the character stream produced by the previous
phases into an octet stream.
Note: Serialization is only defined in terms of encoding the result as a stream of octets. However, a serializer may provide an option that allows the encoding phase to be skipped, so that the result of serialization is a stream of Unicode characters. The effect of any such option is implementation-defined, and a serializer is not required to support such an option.
The XML output method serializes the normalized sequence as an XML entity that MUST satisfy the rules for either a well-formed XML document entity or a well-formed XML external general parsed entity, or both. A serialization error [err:SERE0003] results if the serializer is unable to satisfy those rules, except for content modified by the character expansion phase of serialization, as described in 4 Phases of Serialization. The effects of the character expansion phase could result in the serialized output being not well-formed, but will not result in a serialization error. If a serialization error results, the serializer MUST signal the error.
If the document node of the normalized sequence has a single element node child and no text node children, then the serialized output is a well-formed XML document entity, and the serialized output MUST conform to the appropriate version of the XML Namespaces Recommendation [XML Names] or [XML Names 1.1]. If the normalized sequence does not take this form, then the serialized output is a well-formed XML external general parsed entity, which, when referenced within a trivial XML document wrapper like this:
<?xml version="version"?> <!DOCTYPE doc [ <!ENTITY e SYSTEM "entity-URI"> ]> <doc>&e;</doc>
where entity-URI
is a URI for the entity, and the
value of the version
pseudo-attribute is the value of
the version
parameter, produces a document which
MUST itself be a well-formed XML document
conforming to the corresponding version of the XML Namespaces
Recommendation [XML Names] or [XML Names 1.1].
[Definition: A reconstructed tree may be constructed by parsing the XML document and converting it into an instance of the data model as specified in [XQuery 1.0 and XPath 2.0 Data Model].] The result of serialization MUST be such that the reconstructed tree is the same as the result tree except for the following permitted differences:
If the document was produced by adding a document wrapper, as
described above, then it will contain an extra doc
element as the document element.
The order of attribute and namespace nodes in the two trees MAY be different.
The following properties of corresponding nodes in the two trees MAY be different:
The reconstructed tree MAY contain additional attributes and text nodes resulting from the expansion of default and fixed values in its DTD or schema; also, in the presence of a DTD, non-CDATA attributes may lose whitespace characters as a result of attribute value normalization.
The type annotations of the nodes in the two trees MAY be different. Type annotations in a result tree are discarded when the tree is serialized. Any new type annotations obtained by parsing the document will depend on whether the serialized XML document is assessed against a schema, and this MAY result in type annotations that are different from those in the original result tree.
Note: In order to influence the type annotations in the instance of the data model that would result from processing a serialized XML document, the author of the XSLT stylesheet, XQuery expression or other process might wish to create the instance of the data model that is input to the serialization process so that it makes use of mechanisms provided by [XML Schema], such as
xsi:type
andxsi:schemaLocation
attributes. The serialization process will not automatically create such attributes in the serialized document if those attributes were not part of the result tree that is to be serialized.Similarly, it is possible that an element node in the instance of the data model that is to be serialized has the
nilled
property with the valuetrue
, but noxsi:nil
attribute. The serialization process will not create such an attribute in the serialized document simply to reflect the value of the property. The value of thenilled
property has no direct effect on the serialized result.
Additional namespace nodes MAY be present in the reconstructed tree if the serialization process did not undeclare one or more namespaces, as described in 5.1.7 XML Output Method: the undeclare-prefixes Parameter, and the starting instance of the data model contained an element node with a namespace node that declared some prefix, but a child element of that node did not have any namespace node that declared the same prefix.
The result tree MAY contain namespace nodes that are not present in the reconstructed tree, as the process of creating an instance of the data model MAY ignore namespace declarations in some circumstances. See Section 6.2.3 Construction from an InfosetDM and Section 6.2.4 Construction from a PSVIDM of [XQuery 1.0 and XPath 2.0 Data Model] for additional information.
If the indent
parameter has the value
yes
,
additional text nodes consisting of whitespace characters MAY be present in the reconstructed tree; and
text nodes in the result tree that contained only whitespace characters MAY correspond to text nodes in the reconstructed tree that contain additional whitespace characters that were not present in the result tree
See 5.1.3 XML Output Method: the indent
Parameter for more information on the indent
parameter.
Additional nodes MAY be present in the reconstructed tree due to the effect of character mapping in the character expansion phase, and the values of attribute nodes and text nodes in the reconstructed tree MAY be different from those in the result tree, due to the effects of URI expansion, character mapping and Unicode Normalization in the character expansion phase of serialization.
Note: The
use-character-maps
parameter can cause arbitrary characters to be inserted into the serialized XML document in an unescaped form, including characters that would be considered to be part of XML markup. Such characters could result in arbitrary new element nodes, attribute nodes, and so on, in the reconstructed tree that results from processing the serialized XML document.
A consequence of this rule is that certain characters
MUST be output as character references, to ensure
that they survive the round trip through serialization and parsing.
Specifically, CR, NEL and LINE SEPARATOR characters in text
nodes MUST be
output respectively as "
",
"…
", and "

", or
their equivalents; while CR, NL, TAB, NEL and LINE SEPARATOR
characters in attribute nodes
MUST be output respectively as
"
", "

",
"
", "…
", and
"

", or their equivalents. In addition, the
non-whitespace control characters #x1 through #x1F and #x7F through
#x9F in text nodes and
attribute nodes
MUST be output as character references.
For example, an attribute with the value "x" followed by "y"
separated by a newline will result in the output
"x
y"
(or with any equivalent character
reference). The XML output cannot be "x" followed by a literal
newline followed by a "y" because after parsing, the attribute
value would be "x y"
as a consequence of the XML
attribute normalization rules.
Note: XML 1.0 did not permit an XML processor to normalize NEL or LINE SEPARATOR characters to a LINE FEED character. However, if a document entity that specifies version 1.1 invokes an external general parsed entity with no text declaration or a text declaration that specifies version 1.0, the external parsed entity is processed according to the rules of XML 1.1. For this reason, NEL and LINE SEPARATOR characters in text and attribute nodes must always be escaped using character references, regardless of the value of the
version
parameter.XML 1.0 permitted control characters in the range #x7F through #x9F to appear as literal characters in an XML document, but XML 1.1 requires such characters, other than NEL, to be escaped as character references. An external general parsed entity with no text declaration or a text declaration that specifies a version pseudo-attribute with value
1.0
that is invoked by an XML 1.1 document entity must follow the rules of XML 1.1. Therefore, the non-whitespace control characters in the ranges #x1 through #x1F and #x7F through #x9F must always be escaped, regardless of the value of theversion
parameter.
It is a serialization error [err:SEPM0004] to specify the
doctype-system parameter, or to specify the standalone parameter
with a value other than omit
, if the instance of the
data model contains text nodes
or multiple element nodes as
children of the root node. The
serializer
MUST either signal the error, or recover by
ignoring the request to output a document type declaration or
standalone
parameter.
version
ParameterThe version
parameter specifies the version of XML
and the version of Namespaces in XML to be used for outputting the
instance of the data model. The version output in the XML
declaration (if an XML declaration is not omitted)
MUST correspond to the version of XML that the
serializer used for
outputting the instance of the data model. The value of the
version
parameter MUST match the
VersionNum
XML production of the XML Recommendation
[XML10] or [XML11].
A serialization error [err:SESU0013] results if the value of the
version
parameter specifies a version of XML that is
not supported by the serializer; the serializer MUST signal the
error.
If the serialized result would contain an NCName
Names that contains a character that is
not permitted by the version of Namespaces in XML specified by the
version
parameter, a serialization error [err:SERE0005] results. The serializer
MUST signal the error.
If the serialized result would contain a character that is not
permitted by the version of XML specified by the
version
parameter, a serialization error [err:SERE0006] results. The serializer
MUST signal the error.
For example, if the version
parameter has the value
1.0
, and the instance of the data model contains a
non-whitespace control character in the range #x1 to #x1F, a
serialization
error [err:SERE0006] results. If the
version
parameter has the value 1.1
and a
comment node in the instance of
the data model contains a non-whitespace control character in the
range #x1 to #x1F or a control character other than NEL in the
range #x7F to #x9F, a serialization error [err:SERE0006] results.
encoding
ParameterThe encoding
parameter specifies the encoding to be
used for outputting the instance of the data model. Serializers are
REQUIRED to support values of UTF-8
and UTF-16
. A serialization error [err:SESU0007] occurs if an output encoding
other than UTF-8
or UTF-16
is requested
and the serializer
does not support that encoding. The serializer MUST signal the
error, or recover by using UTF-8
or
UTF-16
instead. The serializer MUST NOT use an
encoding whose name does not match the EncName
XML production of the XML Recommendation
[XML10].
When outputting a newline character in the instance of the data model, the serializer is free to represent it using any character sequence that will be normalized to a newline character by an XML parser, unless a specific mapping for the newline character is provided in a character map (see 9 Character Maps).
When outputting any other character that is defined in the selected encoding, the character MUST be output using the correct representation of that character in the selected encoding.
It is possible that the instance of the data model will contain a character that cannot be represented in the encoding that the serializer is using for output. In this case, if the character occurs in a context where XML recognizes character references (that is, in the value of an attribute node or text node), then the character MUST be output as a character reference. A serialization error [err:SERE0008] occurs if such a character appears in a context where character references are not allowed (for example, if the character occurs in the name of an element). The serializer MUST signal the error.
For example, if a text node
contains the character LATIN SMALL LETTER E WITH ACUTE (#xE9), and
the value of the encoding
parameter is
US-ASCII
, the character MUST be
serialized as a character reference. If a comment node contains the same character, a serialization error
[err:SERE0008]
results.
indent
ParameterIf the indent
parameter has the value
yes
, then the XML output method MAY
output whitespace in addition to the whitespace in the instance of
the data model in order to indent the result so that a person will
find it easier to read; if the indent
parameter has
the value no
, it MUST NOT output any
additional whitespace. If the XML output method does output
additional whitespace, it MUST use an algorithm to
output additional whitespace that satisfies all of the following
constraints:
Whitespace characters MUST NOT be added adjacent to a text node that contains non-whitespace characters.
Whitespace characters MUST NOT be added other than adjacent to an element node, that is, immediately before a start tag or immediately after an end tag.
Whitespace characters MUST NOT be inserted in a
part of the result document that is controlled by an
xml:space
attribute with value preserve
.
(See [XML10] for more information about the
xml:space
attribute.)
Whitespace characters SHOULD NOT be added in
places where the characters would constitute significant
whitespace, for example, in the content of an element that is
annotated with a type other than xs:untyped
or
xs:anyType
, and whose content model is known to
be mixed.
In any location where the above rules allow the addition of whitespace characters, existing whitespace characters MAY also be removed or replaced. For example, a tab MAY be inserted as a replacement for existing spaces.
Note: The effect of these rules is to ensure that whitespace is only added in places where (a) XSLT's
<xsl:strip-space>
declaration could cause it to be removed, and (b) it does not affect the string value of any element node with simple content. It is usually not safe to indent document types that include elements with mixed content.
Note: The whitespace added may possibly be based on whitespace stripped from either the source document or the stylesheet (in the case of XSLT), or guided by other means that might depend on the host language, in the case of an instance of the data model created using some other process.
cdata-section-elements
ParameterThe cdata-section-elements
parameter contains a
list of expanded QNames. If the expanded QName of the parent of a
text node is a member of the
list, then the text node
MUST be output as a CDATA section, except in those
circumstances described below.
If the text node contains
the sequence of characters ]]>
, then the currently
open CDATA section MUST be closed following the
]]
and a new CDATA section opened before the
>
.
If the text node contains characters that are not representable in the character encoding being used to output the instance of the data model, then the currently open CDATA section MUST be closed before such characters, the characters MUST be output using character references or entity references, and a new CDATA section MUST be opened for any further characters in the text node.
CDATA sections MUST NOT be used except where
they have been explicitly requested by the user, either by using
the cdata-section-elements
parameter, or by using some
other implementation-defined mechanism.
Note: This is phrased to permit an implementor to provide an option that attempts to preserve CDATA sections present in the source document.
omit-xml-declaration
and standalone
ParametersThe XML output method MUST output an XML
declaration if the omit-xml-declaration
parameter has
the value no
. The XML declaration
MUST include both version information and an
encoding declaration. If the standalone
parameter has
the value yes
or the value no
, the XML
declaration MUST include a standalone document
declaration with the same value as the value of the
standalone
parameter. If the standalone
parameter has the value omit
, the XML declaration
MUST NOT include a standalone document
declaration; this ensures that it is both an XML declaration
(allowed at the beginning of a document entity) and a text
declaration (allowed at the beginning of an external general parsed
entity).
A serialization error [err:SEPM0009] results if the
omit-xml-declaration
parameter has the value
yes
, and
the standalone
parameter has a value other than
omit
; or
the version
parameter has a value other than
1.0
and the doctype-system
parameter is
specified.
Otherwise, if the omit-xml-declaration
parameter
has the value yes
, the XML output method MUST
NOT output an XML declaration.
doctype-system
and
doctype-public
ParametersIf the doctype-system
parameter is specified, the
XML output method MUST output a document type
declaration immediately before the first element. The name
following <!DOCTYPE
MUST be the
name of the first element, if any. If the
doctype-public
parameter is also specified, then the
XML output method MUST output PUBLIC
followed by the public identifier and then the system identifier;
otherwise, it MUST output SYSTEM
followed by the system identifier. The internal subset
MUST be empty. The doctype-public
parameter MUST be ignored unless the
doctype-system
parameter is specified.
undeclare-prefixes
ParameterThe Data Model allows an element node that binds a non-empty prefix to have a child
element node that does not bind
that same prefix. In Namespaces in XML 1.1 ([XML Names 1.1]), this can be represented
accurately by undeclaring prefixes. For the undeclaring prefix of
the child element node, if the undeclare-prefixes
parameter has the value yes
, the output method is XML
or XHTML, and the version
parameter value is greater
than 1.0
, the serializer MUST undeclare its
namespace. If the undeclare-prefixes
parameter has the
value no
and the output method is XML or XHTML, then
the undeclaration of prefixes MUST NOT occur.
Consider an element x:foo
with four in-scope
namespaces that associate prefixes with URIs as follows:
x
is associated with
http://example.org/x
y
is associated with
http://example.org/y
z
is associated with
http://example.org/z
xml
is associated with
http://www.w3.org/XML/1998/namespace
Suppose that it has a child element x:bar
with
three in-scope namespaces:
x
is associated with
http://example.org/x
y
is associated with
http://example.org/y
xml
is associated with
http://www.w3.org/XML/1998/namespace
If namespace undeclaration is in effect, it will be serialized this way:
<x:foo xmlns:x="http://example.org/x" xmlns:y="http://example.org/y" xmlns:z="http://example.org/z"> <x:bar xmlns:z="">...</x:bar> </x:foo>
In Namespaces in XML 1.0 ([XML
Names]), prefix undeclaration is not possible. If the output
method is XML or XHTML, the value of the
undeclare-prefixes
parameter is yes
, and
the value of the version
parameter is
1.0
, a serialization error [err:SEPM0010] results; the serializer
MUST signal the error.
normalization-form
ParameterThe normalization-form
parameter is applicable to
the XML output method. The values NFC
and
none
MUST be supported by the
serializer. A
serialization
error [err:SESU0011] results if the value of the
normalization-form
parameter specifies a normalization
form that is not supported by the serializer; the serializer MUST signal the
error.
The meanings associated with the possible values of the
normalization-form
parameter are as follows:
NFC
specifies the serialized result will be in
Normalization Form C, using the rules specified in [Character Model for the World Wide Web 1.0:
Normalization].
NFD
specifies the serialized result will be in
Normalization Form D, as specified in [UAX #15: Unicode Normalization
Forms].
NFKC
specifies the serialized result will be in
Normalization Form KC, as specified in [UAX #15: Unicode Normalization
Forms].
NFKD
specifies the serialized result will be in
Normalization Form KD, as specified in [UAX #15: Unicode Normalization
Forms].
fully-normalized
specifies the serialized result
will be in fully normalized text, as specified in [Character Model for the World Wide Web 1.0:
Normalization].
none
specifies that no Unicode
Normalization will be applied.
An implementation-defined value has an implementation-defined effect.
If the value of the parameter is fully-normalized
,
then no relevant construct of the parsed entity created by
the serializer may
start with a composing character. The term relevant
construct has the meaning defined in section 2.13 of [XML11]. If this condition is not satisfied, a
serialization
error [err:SERE0012] MUST be
signaled.
Note: Specifying
fully-normalized
as the value of this parameter does not guarantee that the XML document output by the serializer will in fact be fully normalized as defined in [XML11]. This is because the serializer does not check that the text isinclude normalized
, which would involve checking all external entities that it refers to (such as an external DTD). Furthermore, the serializer does not check whether any character escape generated using character maps represents a composing character.
media-type
ParameterThe media-type
parameter is applicable to the XML
output method. See 3 Serialization
Parameters for more information.
use-character-maps
ParameterThe use-character-maps
parameter is applicable to
the XML output method. The result of serialization using the XML
output method is not guaranteed to be well-formed XML if character
maps have been specified. See 9
Character Maps for more information.
byte-order-mark
ParameterThe byte-order-mark
parameter is applicable to the
XML output method. See 3 Serialization
Parameters for more information.
Note: The byte order mark may be undesirable under certain circumstances; for example, to concatenate resulting XML fragments without additional processing to remove the byte order mark. Therefore this specification does not mandate the
byte-order-mark
parameter to have the valueyes
when the encoding is UTF-16, even though the XML 1.0 and XML 1.1 specifications state that entities encoded in UTF-16 must begin with a byte order mark. Consequently, this specification does not guarantee that the resulting XML fragment, without a byte order mark, will not cause an error when processed by a conforming XML processor.
escape-uri-attributes
ParameterThe escape-uri-attributes
parameter is not
applicable to the XML output method. It is the responsibility of
the host
language to specify whether an error occurs if this parameter
is specified in combination with the XML output method, or if the
parameter is simply dropped.
include-content-type
ParameterThe include-content-type
parameter is not
applicable to the XML output method. It is the responsibility of
the host
language to specify whether an error occurs if this parameter
is specified in combination with the XML output method, or if the
parameter is simply dropped.
The XHTML output method serializes the instance of the data model as XML, using the HTML compatibility guidelines defined in the XHTML specification.
It is entirely the responsibility of the person or process that creates the instance of the data model to ensure that the instance of the data model conforms to the [XHTML 1.0] or [XHTML 1.1] specification. It is not an error if the instance of the data model is invalid XHTML. Equally, it is entirely under the control of the person or process that creates the instance of the data model whether the output conforms to XHTML 1.0 Strict, XHTML 1.0 Transitional, or any other specific definition of XHTML.
The serialization of the instance of the data model follows the same rules as for the XML output method, with the general exceptions noted below and parameter-specific exceptions in 6.1 The Influence of Serialization Parameters upon the XHTML Output Method. These differences are based on the HTML compatibility guidelines published in Appendix C of [XHTML 1.0], which are designed to ensure that as far as possible, XHTML is rendered correctly on user agents designed originally to handle HTML.
[Definition: The following XHTML elements have an
EMPTY content model: area
, base
,
br
, col
, hr
,
img
, input
, link
,
meta
, basefont
, frame
,
isindex
, and param
.] Given an empty
instance of an XHTML element whose content model is not EMPTY (for example, an empty title
or paragraph) the serializer MUST NOT use the
minimized form. That is, it MUST output
<p></p>
and not
<p />
.
If an element that has no children is an XHTML element
with an EMPTY content
model, the serializer MUST use the
minimized tag syntax, for example <br />
,
as the alternative syntax <br></br>
allowed by XML gives uncertain results in many existing user
agents. The serializer
MUST include a space before the trailing
/>
, e.g. <br />
,
<hr />
and
<img src="karen.jpg" alt="Karen" />
.
The serializer
MUST NOT use the entity reference
'
which, although legal in XML and therefore
in XHTML, is not defined in HTML and is not recognized by all HTML
user agents.
The serializer
SHOULD output namespace declarations in a way that
is consistent with the requirements of the XHTML DTD if this is
possible. The XHTML 1.0 DTDs require the declaration
xmlns="http://www.w3.org/1999/xhtml"
to appear on the
html
element, and only on the html
element. The serializer MUST output namespace
declarations that are consistent with the namespace nodes present in the result tree, but it MUST
avoid outputting redundant namespace declarations on elements where
the DTD would make them invalid.
Note: If the
html
element is generated by an XSLT literal result element of the form<html xmlns="http://www.w3.org/1999/xhtml"> ... </html>
, or by an XQuery direct element constructor of the same form, then thehtml
element in the result document will have a node name whose prefix is "", which will satisfy the requirements of the DTD. In other cases the prefix assigned to the element is implementation-dependent.
Note: Appendix C of [XHTML 1.0] describes a number of compatibility guidelines for users of XHTML who wish to render their XHTML documents with HTML user agents. In some cases, such as the guideline on the form empty elements should take, only the serialization process itself has the ability to follow the guideline. In such cases, those guidelines are reflected in the requirements on the serializer described above.
In all other cases, the guidelines can be adhered to by the instance of the data model that is input to the serialization process. The guideline on the use of whitespace characters in attribute values is one such example. Another example is that
xml:lang="..."
does not serialize to bothxml:lang="..."
andlang="..."
as required by some legacy user agents. It is the responsibility of the person or process that creates the instance of the data model that is input to the serialization process to ensure it is created in a way that is consistent with the guidelines. No serialization error results if the input instance of the data model does not adhere to the guidelines.
version
ParameterThe behavior for version
parameter for the XHTML
output method is described in 5.1.1 XML
Output Method: the version Parameter.
encoding
ParameterThe behavior for encoding
parameter for the XHTML
output method is described in 5.1.2 XML
Output Method: the encoding Parameter.
indent
ParameterIf the indent
parameter has the value
yes
, the serializer MAY add or remove
whitespace as it serializes the result tree, if it observes the following
constraints.
Whitespace MUST NOT be added other than before or after an element, or adjacent to an existing whitespace character.
Whitespace MUST NOT be added or removed
adjacent to an inline element. The inline elements are those
elements in the XHTML namespace in the %inline category of any of
the XHTML 1.0 DTD's, in the %inline.class category of the XHTML 1.1
DTD, and elements in the XHTML namespace with local names
ins
and del
if they are used as inline
elements (i.e., if they do not contain element
children).
Whitespace MUST NOT be added or removed
inside a formatted element, the formatted elements being those in
the XHTML namespace with local names pre
,
script
, style
, and
textarea
.
Note: The effect of the above constraints is to ensure any insertion or deletion of whitespace would not affect how a conforming HTML user agent would render the output, assuming the serialized document does not refer to any HTML style sheets.
The HTML definition of whitespace is different from the XML definition: see section 9.1 of [HTML] 4.01 specification.
cdata-section-elements
ParameterThe behavior for cdata-section-elements
parameter
for the XHTML output method is described in 5.1.4 XML Output Method: the
cdata-section-elements Parameter.
omit-xml-declaration
and standalone
ParametersThe behavior for omit-xml-declaration
and
standalone
parameters for the XHTML output method is
described in 5.1.5 XML
Output Method: the omit-xml-declaration and standalone
Parameters.
Note: As with the XML output method, the XHTML output method specifies that an XML declaration will be output unless it is suppressed using the
omit-xml-declaration
parameter. Appendix C.1 of [XHTML 1.0] provides advice on the consequences of including, or omitting, the XML declaration.
doctype-system
and
doctype-public
ParametersThe behavior for doctype-system
and
doctype-public
parameters for the XHTML output method
is described in 5.1.6 XML Output Method:
the doctype-system and doctype-public Parameters.
undeclare-prefixes
ParameterThe behavior for undeclare-prefixes
parameter for
the XHTML output method is described in 5.1.7 XML Output Method: the
undeclare-prefixes Parameter.
normalization-form
ParameterThe behavior for normalization-form
parameter for
the XHTML output method is described in 5.1.8 XML Output Method: the
normalization-form Parameter.
media-type
ParameterThe behavior for media-type
parameter for the XHTML
output method is described in 5.1.9
XML Output Method: the media-type Parameter.
use-character-maps
ParameterThe behavior for use-character-maps
parameter for
the XHTML output method is described in 5.1.10 XML Output Method: the
use-character-maps Parameter.
byte-order-mark
ParameterThe behavior for byte-order-mark
parameter for the
XHTML output method is described in 5.1.11 XML Output Method: the
byte-order-mark Parameter.
escape-uri-attributes
ParameterIf the escape-uri-attributes
parameter has the
value yes
, the XHTML output method
MUST apply URI escaping to URI attribute values, except that
relative URIs MUST NOT be absolutized.
Note: This escaping is deliberately confined to non-ASCII characters, because escaping of ASCII characters is not always appropriate, for example when URIs or URI fragments are interpreted locally by the HTML user agent. Even in the case of non-ASCII characters, escaping can sometimes cause problems. More precise control of URI escaping is therefore available by setting
escape-uri-attributes
tono
, and controlling the escaping of URIs by using methods defined in Section 7.4.10 fn:encode-for-uriFO and Section 7.4.11 fn:iri-to-uriFO.
include-content-type
ParameterIf the instance of the data model includes a head
element in the XHTML namespace, and the
include-content-type
parameter has the value
yes
, the XHTML output method MUST add
a meta
element as the first child element of the
head
element, specifying the character encoding
actually used.
For example,
<head> <meta http-equiv="Content-Type" content="text/html; charset=EUC-JP" /> ...
The content type SHOULD be set to the value
given for the media-type
parameter.
Note: It is recommended that the host language use as default value for this parameter one of the MIME types ([RFC2046]) registered for XHTML. Currently, these are
text/html
(registered by [RFC2854]) andapplication/xhtml+xml
(registered by [RFC3236]). Note that some user agents fail to recognize the charset parameter if the content type is nottext/html
.
If a meta
element has been added to the
head
element as described above, then any existing
meta
element child of the head
element
having an http-equiv
attribute with the value
"Content-Type", making the comparison without consideration of
casing and leading/trailing spaces, MUST be
discarded.
Note: This process removes possible parameters in the attribute value. For example,
<meta http-equiv="Content-Type" content="text/html;version='3.0'" />in the data model instance would be replaced by,
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
The HTML output method serializes the instance of the data model as HTML.
For example, the following XSL stylesheet generates html output,
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:output method="html" version="4.0"/> <xsl:template match="/"> <html> <xsl:apply-templates/> </html> </xsl:template> ... </xsl:stylesheet>
In the example, the version
attribute of the
xsl:output
element indicates the version of the HTML
Recommendation [HTML] to which the
serialized result is to conform.
It is entirely the responsibility of the person or process that creates the instance of the data model to ensure that the instance of the data model conforms to the HTML Recommendation [HTML]. It is not an error if the instance of the data model is invalid HTML. Equally, it is entirely under the control of the person or process that creates the instance of the data model whether the output conforms to HTML.
The HTML output method MUST NOT output an
element differently from the XML output method unless the expanded
QName of the element has a null namespace URI. [Definition: An element whose
expanded QName has a non-null namespace URI
MUST be output as XML. This is known as an XML
Island.] If the expanded QName of the element has a null namespace
URI, but the local part of the expanded QName is not recognized
as the name of an HTML element, the element MUST
be output in the same way as a non-empty, inline element such as
span
. In particular:
If the result
tree contains namespace nodes for namespaces other than the XML namespace,
the HTML output method MUST represent these
namespaces using attributes named xmlns
or
xmlns:
prefix in the same way as the XML
output method would represent them when the version
parameter is set to 1.0
.
If the result
tree contains elements or attributes whose names have a
non-null namespace URI, the HTML
output method MUST generate namespace-prefixed
QNames for these nodes in the
same way as the XML output method would do when the
version
parameter is set to 1.0
.
Where special rules are defined later in this section for serializing specific HTML elements and attributes, these rules MUST NOT be applied to an element or attribute whose name has a non-null namespace URI. However, the generic rules for the HTML output method that apply to all elements and attributes, for example the rules for escaping special characters in the text and the rules for indentation, MUST be used also for namespaced elements and attributes.
When serializing an element whose name is not defined in the
HTML specification, but that is in the null namespace, the HTML
output method MUST apply the same rules (for
example, indentation rules) as when serializing a span
element. The descendants of such an element MUST
be serialized as if they were descendants of a span
element.
When serializing an element whose name is in a non-null
namespace, the HTML output method MUST apply the
same rules (for example, indentation rules) as when serializing a
div
element. The descendants of such an element
MUST be serialized as if they were descendants of
a div
element. , except for the influence of the
cdata-section-elements
serialization parameter on any
text node children of the element.
The HTML output method MUST NOT output an
end-tag for an empty element if the element type has an empty
content model. For HTML 4.0, the element types that
have an empty content model are area
,
base
, basefont
, br
,
col
, frame
, hr
,
img
, input
, isindex
,
link
, meta
and param
. For
example, an element written as <br/>
or
<br></br>
in an XSLT stylesheet
MUST be output as <br>
.
The HTML output method MUST recognize the names
of HTML elements regardless of case. For example, elements named
br
, BR
or Br
MUST all be recognized as the HTML br
element and output without an end-tag.
The HTML output method MUST NOT perform
escaping for the content of the script
and
style
elements.
For example, a script
element created by an XQuery
direct element constructor or an XSLT literal result element, such
as:
<script>if (a < b) foo()</script>
or
<script><![CDATA[if (a < b) foo()]]></script>
MUST be output as
<script>if (a < b) foo()</script>
A common requirement is to output a script
element
as shown in the example below:
<script type="application/ecmascript"> document.write ("<em>This won't work</em>") </script>
This is illegal HTML, for the reasons explained in section B.3.2 of the [HTML] 4.01 specification. Nevertheless, it is possible to output this fragment, using either of the following constructs:
Firstly, by use of a script
element created by an
XQuery direct element constructor or an XSLT literal result
element:
<script type="application/ecmascript"> document.write ("<em>This won't work</em>") </script>
Secondly, by constructing the markup from ordinary text characters:
<script type="application/ecmascript"> document.write ("<em>This won't work</em>") </script>
As the [HTML] specification points out, the correct way to write this is to use the escape conventions for the specific scripting language. For JavaScript, it can be written as:
<script type="application/ecmascript"> document.write ("<em>This will work<\/em>") </script>
The [HTML] 4.01 specification also shows examples of how to write this in various other scripting languages. The escaping MUST be done manually; it will not be done by the serializer.
The HTML output method MUST NOT escape
"<
" characters occurring in attribute values.
The HTML output method MUST output boolean attributes (that is attributes with only a single allowed value that is equal to the name of the attribute) in minimized form.
For example, a start-tag created using the following XQuery direct element constructor or XSLT literal result element
<OPTION selected="selected">
MUST be output as
<OPTION selected>
The HTML output method MUST NOT escape a
&
character occurring in an attribute value
immediately followed by a {
character (see Section
B.7.1 of the HTML Recommendation [HTML]).
For example, a start-tag created using the following XQuery direct element constructor or XSLT literal result element
<BODY bgcolor='&{{randomrbg}};'>
MUST be output as
<BODY bgcolor='&{randomrbg};'>
See 7.4 The Influence of Serialization Parameters upon the HTML Output Method for additional directives on how attributes may be written.
The HTML output method MAY output a character
using a character entity reference in preference to using a numeric
character reference, if an entity is defined for the character in
the version of HTML that the output method is using. Entity
references and character references SHOULD be used
only where the character is not present in the selected encoding,
or where the visual representation of the character is unclear (as
with
, for example).
When outputting a sequence of whitespace characters in the
instance of the data model, within an element where whitespace is
treated normally (but not in elements such as pre
and
textarea
), the HTML output method MAY
represent it using any sequence of whitespace that will be treated
in the same way by an HTML user agent. See section 3.5 of [XHTML Modularization] for some
additional information on handling of whitespace by an HTML user
agent.
Certain characters, specifically the control characters #x7F-#x9F, are legal in XML but not in HTML. It is a serialization error [err:SERE0014] to use the HTML output method when such characters appear in the instance of the data model. The serializer MUST signal the error.
The HTML output method MUST terminate
processing instructions with >
rather than
?>
. It is a serialization error [err:SERE0015] to use the HTML output
method when >
appears within a processing
instruction in the data model instance being serialized.
version
ParameterThe version
attribute indicates the version of the
HTML Recommendation [HTML] to which the
serialized result is to conform. If the serializer does not support the version of HTML
specified by this parameter, it MUST signal a
serialization
error [err:SESU0013].
encoding
ParameterThe encoding
parameter specifies the encoding to be
used. Serializers are
REQUIRED to support values of UTF-8
and UTF-16
. A serialization error [err:SESU0007] occurs if an output encoding
other than UTF-8
or UTF-16
is requested
and the serializer
does not support that encoding. The serializer MUST signal the
error.
It is possible that the instance of the data model will contain
a character that cannot be represented in the encoding that the
serializer is using
for output. In this case, if the character occurs in a context
where HTML recognizes character references, then the character
MUST be output as a character entity reference or
decimal numeric character reference; otherwise (for example, in a
script
or style
element or in a comment),
the serializer
MUST signal a serialization error [err:SERE0008].
See 7.4.13 HTML Output
Method: the include-content-type Parameter regarding how
this parameter is used with the include-content-type
parameter.
indent
ParameterIf the indent
parameter has the value
yes
, then the HTML output method MAY
add or remove whitespace as it serializes the result tree, if it
observes the following constraints.
Whitespace MUST NOT be added other than before or after an element, or adjacent to an existing whitespace character.
Whitespace MUST NOT be added or removed
adjacent to an inline element. The inline elements are those
included in the %inline
category of any of the HTML
4.01 DTD's, as well as the ins
and del
elements if they are used as inline elements (i.e., if they do not
contain element children).
Whitespace MUST NOT be added or removed
inside a formatted element, the formatted elements being
pre
, script
, style
, and
textarea
.
Note: The effect of the above constraints is to ensure any insertion or deletion of whitespace would not affect how a conforming HTML user agent would render the output, assuming the serialized document does not refer to any HTML style sheets.
Note that the HTML definition of whitespace is different from the XML definition (see section 9.1 of the [HTML] specification).
cdata-section-elements
ParameterThe cdata-section-elements
parameter is not
applicable to the HTML output method, except in the case of
XML Islands.
omit-xml-declaration
and standalone
ParametersThe omit-xml-declaration
and
standalone
parameters are not applicable to the HTML
output method.
doctype-system
and
doctype-public
ParametersIf the doctype-public
or
doctype-system
parameters are specified, then the HTML
output method MUST output a document type
declaration immediately before the first element. The name
following <!DOCTYPE
MUST be
HTML
or html
. If the
doctype-public
parameter is specified, then the output
method MUST output PUBLIC
followed by
the specified public identifier; if the doctype-system
parameter is also specified, it MUST also output
the specified system identifier following the public identifier. If
the doctype-system
parameter is specified but the
doctype-public
parameter is not specified, then the
output method MUST output SYSTEM
followed by the specified system identifier.
undeclare-prefixes
ParameterThe undeclare-prefixes
parameter is not applicable
to the HTML output method.
normalization-form
ParameterThe normalization-form
parameter is applicable to
the HTML output method. The values NFC
and
none
MUST be supported by the
serializer. A
serialization
error [err:SESU0011] results if the value of the
normalization-form
parameter specifies a normalization
form that is not supported by the serializer; the serializer MUST signal the
error.
media-type
ParameterThe media-type
parameter is applicable to the HTML
output method. See 3 Serialization
Parameters for more information. See 7.4.13 HTML Output Method: the
include-content-type Parameter regarding how this parameter
is used with the include-content-type
parameter.
use-character-maps
ParameterThe use-character-maps
parameter is applicable to
the HTML output method. See 9
Character Maps for more information.
byte-order-mark
ParameterThe byte-order-mark
parameter is applicable to the
HTML output method. See 3 Serialization
Parameters for more information.
escape-uri-attributes
ParameterIf the escape-uri-attributes
parameter has the
value yes
, the HTML output method
MUST apply URI escaping to URI attribute values, except that
relative URIs MUST NOT be absolutized.
Note: This escaping is deliberately confined to non-ASCII characters, because escaping of ASCII characters is not always appropriate, for example when URIs or URI fragments are interpreted locally by the HTML user agent. Even in the case of non-ASCII characters, escaping can sometimes cause problems. More precise control of URI escaping is therefore available by setting
escape-uri-attributes
tono
, and controlling the escaping of URIs by using methods defined in Section 7.4.10 fn:encode-for-uriFO and Section 7.4.11 fn:iri-to-uriFO.
include-content-type
ParameterIf there is a head
element, and the
include-content-type
parameter has the value
yes
, the HTML output method MUST add
a meta
element as the first child element of the
head
element specifying the character encoding
actually used.
For example,
<HEAD> <META http-equiv="Content-Type" content="text/html; charset=EUC-JP"> ...
The content type MUST be set to the value given
for the media-type
parameter.
If a meta
element has been added to the
head
element as described above, then any existing
meta
element child of the head
element
having an http-equiv
attribute with the value
"Content-Type", making the comparison without consideration
of case and leading or trailing spaces,
MUST be discarded.
Note: This process removes possible parameters in the attribute value. For example,
<meta http-equiv="Content-Type" content="text/html;version='3.0'"/>in the data model instance would be replaced by,
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
The Text output method serializes the instance of the data model by outputting the string value of the document node created by the markup generation step of the phases of serialization without any escaping.
A newline character in the instance of the data model MAY be output using any character sequence that is conventionally used to represent a line ending in the chosen system environment.
version
ParameterThe version
parameter is not applicable to the Text
output method.
encoding
ParameterThe encoding
parameter identifies the encoding that
the Text output method MUST use to convert
sequences of characters to sequences of bytes. Serializers are
REQUIRED to support values of UTF-8
and UTF-16
. A serialization error [err:SESU0007] occurs if the serializer does not support the
encoding specified by the encoding
parameter. The
serializer
MUST signal the error. If the instance of the data
model contains a character that cannot be represented in the
encoding that the serializer is using for output, the serializer
MUST signal a serialization error [err:SERE0008].
indent
ParameterThe indent
parameter is not applicable to the Text
output method.
cdata-section-elements
ParameterThe cdata-section-elements
parameter is not
applicable to the Text output method.
omit-xml-declaration
and standalone
ParametersThe omit-xml-declaration
and
standalone
parameters are not applicable to the Text
output method.
doctype-system
and
doctype-public
ParametersThe doctype-system
and doctype-public
parameters are not applicable to the Text output method.
undeclare-prefixes
ParameterThe undeclare-prefixes
parameter is not applicable
to the Text output method.
normalization-form
ParameterThe normalization-form
parameter is applicable to
the Text output method. The values NFC
and
none
MUST be supported by the
serializer. A
serialization
error [err:SESU0011] results if the value of the
normalization-form
parameter specifies a normalization
form that is not supported by the serializer; the serializer MUST signal the
error.
media-type
ParameterThe media-type
parameter is applicable to the Text
output method. See 3 Serialization
Parameters for more information.
use-character-maps
ParameterThe use-character-maps
parameter is applicable to
the Text output method. See 9
Character Maps for more information.
byte-order-mark
ParameterThe byte-order-mark
parameter is applicable to the
Text output method. See 3 Serialization
Parameters for more information.
The use-character-maps
parameter is a list of
characters and corresponding string substitutions.
Character maps allow a specific character appearing in a text or attribute node in the instance of the data model to be replaced with a specified string of characters during serialization. The string that is substituted is output "as is," and the serializer performs no checks that the resulting document is well-formed. This mechanism can therefore be used to introduce arbitrary markup in the serialized output. See Section 20.1 Character MapsXT of [XSL Transformations (XSLT) Version 2.0] for examples of using character mapping in XSLT.
Character mapping is applied to the characters that actually appear in a text or attribute node in the instance of the data model, before any other serialization operations such as escaping or Unicode Normalization are applied. If a character is mapped, then it is not subjected to XML or HTML escaping, nor to Unicode Normalization. The string that is substituted for a character is not validated or processed in any way by the serializer, except for translation into the target encoding. In particular, it is not subjected to XML or HTML escaping, it is not subjected to Unicode Normalization, and it is not subjected to further character mapping.
Character mapping is not applied to characters in text nodes whose parent elements are listed
in the cdata-section-elements
parameter, nor to
characters for which output escaping has been disabled (disabling
output escaping is an [XSL Transformations (XSLT)
Version 2.0] feature), nor to characters in attribute values
that are subject to URI escaping defined for the HTML and XHTML
output methods, unless URI escaping has been disabled using the
escape-uri-attributes
parameter in the output
definition.
On serialization, occurrences of a character specified in the
use-character-maps
in text nodes and attribute values are replaced by the
corresponding string from the use-character-maps
parameter.
Note: Using a character map can result in non-well-formed documents if the string contains XML-significant characters. For example, it is possible to create documents containing unmatched start and end tags, references to entities that are not declared, or attributes that contain tags or unescaped quotation marks.
If a character is mapped, then it is not subjected to XML or HTML escaping.
A serialization error [err:SERE0008] occurs if character mapping causes the output of a string containing a character that cannot be represented in the encoding that the serializer is using for output. The serializer MUST signal the error.
[Definition: Serialization is intended primarily as a component of a host language such as [XSL Transformations (XSLT) Version 2.0] or [XQuery 1.0: An XML Query Language].] Therefore, this document relies on specifications that use it to specify conformance criteria for Serialization in their respective environments. Specifications that set conformance criteria for their use of Serialization MUST NOT change the semantic definitions of Serialization as given in this specification, except by subsetting and/or compatible extensions. It is the responsibility of the host language to specify how serialization errors should be handled.
Certain facilities in this specification are described as producing implementation-defined results. A claim that asserts conformance with this specification MUST be accompanied by documentation stating the effect of each implementation-defined feature. For convenience, a non-normative checklist of implementation-defined features is provided at D Checklist of Implementation-Defined Features.
This document uses the err
prefix which represents
the same namespace URI (http://www.w3.org/2005/xqt-errors) as
defined in [XML Path Language (XPath) 2.0].
Use of this namespace prefix binding in this document is not
normative.
It is an error if an item in S6 in sequence normalization is an attribute node or a namespace node.
It is an error if the serializer is unable to satisfy the rules for either a well-formed XML document entity or a well-formed XML external general parsed entity, or both, except for content modified by the character expansion phase of serialization.
It is an error to specify the doctype-system parameter, or to
specify the standalone parameter with a value other than
omit
, if the instance of the data model contains text
nodes or multiple element nodes as children of the root node.
It is an error if the serialized result would contain an
NCName
Names that contains a character that is
not permitted by the version of Namespaces in XML specified by the
version
parameter.
It is an error if the serialized result would contain a
character that is not permitted by the version of XML specified by
the version
parameter.
It is an error if an output encoding other than
UTF-8
or UTF-16
is requested and the
serializer does not
support that encoding.
It is an error if a character that cannot be represented in the encoding that the serializer is using for output appears in a context where character references are not allowed (for example if the character occurs in the name of an element).
It is an error if the omit-xml-declaration
parameter has the value yes
, and the
standalone
attribute has a value other than
omit
; or the version
parameter has a
value other than 1.0
and the
doctype-system
parameter is specified.
It is an error if the output method is xml
, the
value of the undeclare-prefixes
parameter is
yes
, and the value of the version
parameter is 1.0.
It is an error if the value of the
normalization-form
parameter specifies a normalization
form that is not supported by the serializer.
It is an error if the value of the
normalization-form
parameter is
fully-normalized
and any relevant construct of the
result begins with a combining character.
It is an error if the serializer does not support the version of XML or
HTML specified by the version
parameter.
It is an error to use the HTML output method when characters which are legal in XML but not in HTML, specifically the control characters #x7F-#x9F, appear in the instance of the data model.
It is an error to use the HTML output method when
>
appears within a processing instruction in the
data model instance being serialized.
It is a an error if a parameter value is invalid for the defined domain.
The following list of attributes are declared as type
%URI
or %UriList
for a given HTML or
XHTML element, with the exception of the name
attribute for element A
which is not a URI type. The
name
attribute for element A
should be
escaped as is recommended by the HTML Recommendation [HTML] in Appendix B.2.1.
| Attributes | Elements |
|---|---|
| action | FORM |
| archive | OBJECT |
| background | BODY |
| cite | BLOCKQUOTE, DEL, INS, Q |
| classid | OBJECT |
| codebase | APPLET, OBJECT |
| data | OBJECT |
| datasrc | BUTTON, DIV, INPUT, OBJECT, SELECT, SPAN, TABLE, TEXTAREA |
| for | SCRIPT |
| href | A, AREA, BASE, LINK |
| longdesc | FRAME, IFRAME, IMG |
| name | A |
| profile | HEAD |
| src | FRAME, IFRAME, IMG, INPUT, SCRIPT |
| usemap | IMG, INPUT, OBJECT |
This appendix provides a summary of Serialization features whose effect is explicitly implementation-defined. The conformance rules (see 10 Conformance) require vendors to provide documentation that explains how these choices have been exercised.
method
serialization parameter, then the parameter specifies an implementation-defined
output method. (See 3 Serialization
Parameters)normalization-form
form
parameter is not NFC
, NFD
,
NFKC
, NFKD
,
fully-normalized
, or none
then the
meaning of the value and its effect is implementation-defined.
(See 5.1.8 XML Output Method:
the normalization-form Parameter)The changes made to this document are described in detail in the Errata to the first edition. The rationale for each erratum is explained in the corresponding Bugzilla database entry. The following table summarizes the errata that have been applied.
| Erratum | Bugzilla | Category | Description |
| E1 | 4372 | substantive | This erratum places constraints on the type of string that is valid for the doctype-public attribute of xsl:output. |
| E2 | 4557 | editorial | This erratum corrects an editorial error concerning the number of phases of serialization. |
| E3 | 5066 | editorial | This erratum corrects an editorial error concerning the currently registered XHTML media types. |
| E4 | 5433 | substantive | This erratum clarifies how descendant elements of an XML island must be serialized according to the HTML output method. |
| E5 | 5439 | substantive | This erratum aligns the description of the effect of the include-content-type serialization parameter of the HTML output method with that of the XHTML output method. |
| E6 | 5458 | substantive | This erratum ensures that the sequence normalization process preserves any type annotations associated with nodes in the input sequence. |
| E7 | 5300 | substantive | This erratum clarifies how elements with empty content models are to be serialized under the HTML and XHTML output methods. |
| E8 | 5441 | substantive | This erratum ensures that Unicode normalization applies to all characters that might be adjacent in the serialized result produced by the text output method, including those that are in text nodes that are separated by element nodes in the data model instance. |
| E9 | 5993 | substantive | This erratum makes previously non-normative text that describes how the xhtml and html output methods must behave if the indent parameter has the value yes into normative text. |
| E10 | 6466 | substantive | This erratum specifies the syntactic constraints on the values of the doctype-public and doctype-system serialization parameters. |
| E11 | 6376 | editorial | This erratum makes clear which parts of the recommendation are not considered to be normative. |


Video Collaboration
Preview camera and microphone
Join room
Name
Room
Join room
Mute
Disable video
Share screen
Start whiteboard
Disconnect
Screenshot
Send
👍
👎
⏪
⏩
☕
😂
👏
❤
⏰
✋
🤦
🎉


Davido reportedly arrested in Dubai in connection to stabbing incident
Dubai. Nigerian singer Davido has reportedly been arrested for allegedly stabbing Michael aka Dream Chaser, who is said to be the younger brother of Abu Abel, the CEO of Obimzy Records in Dubai.
The news of his arrest was shared on Monday morning by Instablog9ja, a Nigerian blog.
According to multiple reports, the incident happened inside an elevator at Crab Market, Emirates Financial Towers, Dubai when the victim approached an already tipsy Davido.
The musician is said to have broken a bottle on the Vitim’s head inflicting injuries.
The police were subsequently called in and the singer was whisked away around 7am, while the victim was rushed to the Kuwait hospital, Deira.
Davido’s manager, Asa, missed his scheduled flight due to the incident.
Advertisement
Together with many other artistes, Davido was in Dubai for the One Africa Music Festival.
On Sunday, the singer had shared on Instagram a photo of himself in a private jet.
Despite the new Instagram post, there are claims that his management has taken over his social media page as part of the damage control moves.


Thanks for dropping by!
My name is Georgie and I am a complete coding beginner. Over the next 8 weeks I will be learning to code using HTML and CSS with CodeFirst:Girls.
I haven't had much, if any exposure to coding and programming before but there's no time like the present to learn a new skill!
On April 1st, I start my new graduate role as UX Content Designer and what better way to prepare than to learn front end programming.
I'm really excited to see where the next 8 weeks takes me and hope you'll enjoy the journey with me!


China Mobile targets 70M 5G users in 2020
by Joseph WaringChina Mobile, the world’s largest mobile operator, set a target of signing up 70 million 5G users by the end of 2020, with a planned investment of CNY20 billion ($2.85 billion), China Daily reported.
Yang Jie, the state-owned operator’s chairman, said during a conference in Guangzhou its 5G investment over the next five years will reach at least CNY100 billion, the newspaper wrote.
Yang said the company will focus on deploying standalone 5G technology.
The market leader registered more than 10 million 5G users even before officially launching 5G services at the end of October in parts of 50 cities, along with rivals China Telecom and China Unicom.
China Mobile aims to deploy 50,000 5G sites by end-December.
GSMA Intelligence forecasts China will have 460 million 5G subscribers by 2025.


Sparse binary linear algebra¶
Binary matrix¶
-
class
pyqec.sparse.
BinaryMatrix
¶ A sparse binary matrix with efficient row access.
- Parameters
num_columns (Int) – The number of columns in the matrix. Must be a non-negative integer.
rows (Seq[Seq[Int]]) – Each sequence in the outer sequence represents a row of the matrix. The inner sequences contain the positions (columns) of entries with value 1 in the corresponding row.
Example
>>> from pyqec.sparse import BinaryMatrix, to_dense >>> matrix = BinaryMatrix(3, [[0, 2], [1], [0, 1]]) >>> to_dense(matrix) array([[1, 0, 1], [0, 1, 0], [1, 1, 0]], dtype=int32)
- Raises
If the number of columns is negative or –
if a position in a row is out of bound. –
-
bitwise_xor
(other)¶ Returns the bitwise xor sum of self and other.
Example
>>> from pyqec.sparse import BinaryMatrix, BinaryVector >>> matrix1 = BinaryMatrix(4, [[0, 1, 2], [1, 2, 3], [1, 2]]) >>> matrix2 = BinaryMatrix(4, [[0, 1], [1, 2], [0, 1, 3]]) >>> matrix.bitwise_xor(matrix2) [2] [3] [0, 2, 3]
- Raises
ValueError – The shapes of the matrices are different.
-
dot_with_matrix
(matrix)¶ Returns the dot product between self and the given matrix.
Example
>>> from pyqec.sparse import BinaryMatrix, BinaryVector >>> matrix1 = BinaryMatrix(4, [[0, 1, 2], [1, 2, 3], [1, 2]]) >>> matrix2 = BinaryMatrix(3, [[0, 1], [1, 2], [0, 1], [1, 2]) >>> matrix.dot_with_matrix(matrix2) [1, 2] [0, 1] [0, 2]
- Raises
ValueError – Number of columns of self is not the same as the number of rows of the other matrix.
-
dot_with_vector
(vector)¶ Returns the dot product between self and the given vector.
Example
>>> from pyqec.sparse import BinaryMatrix, BinaryVector >>> matrix = BinaryMatrix(4, [[0, 1, 2], [1, 2, 3], [1, 2]]) >>> vector = BinaryVector(4, [1, 3]) >>> matrix.dot_with_vector(vector) [0, 2]
- Raises
ValueError – The vector length is not the same as the matrix number of columns.
-
echelon_form
()¶ Performs Gaussian elimination to return the matrix in echelon form.
Example
>>> from pyqec.sparse import BinaryMatrix >>> matrix = BinaryMatrix(4, [[0, 1, 2], [1, 3], [0, 2], [0, 2, 3]]) >>> matrix.echelon_form() [0, 1, 2] [1, 3] [3]
-
element
(row, column)¶ Returns the element at the given row and column.
- Raises
IndexError – The row or column is out of bound.
-
static
empty
()¶ An empty matrix.
Mostly useful as a placeholder since it allocate a minimal amount of memory.
Example
>>> from pyqec.sparse import BinaryMatrix >>> matrix = BinaryMatrix.empty() >>> matrix.num_rows() 0 >>> matrix.num_columns() 0
-
horizontal_concat_with
(other)¶ Returns the horizontal concatenation of self and other matrix.
If the matrices have a different number of rows, the smallest one is padded with zeros.
Example
>>> from pyqec.sparse import BinaryMatrix >>> matrix = BinaryMatrix(4, [[0, 1, 2], [1, 2, 3]]) >>> matrix.horizontal_concat_with(BinaryMatrix.identity(3)) [0, 1, 2, 4] [1, 2, 3, 5] [6]
-
static
identity
(length)¶ An identity matrix of the given length.
Example
>>> from pyqec.sparse import BinaryMatrix, to_dense >>> matrix = BinaryMatrix.identity(3) >>> to_dense(matrix) array([[1, 0, 0], [0, 1, 0], [0, 0, 1]], dtype=int32)
-
is_empty
()¶ Checks if the matrix has shape (0, 0).
-
is_one_at
(row, column)¶ Check if the given element has value 1.
- Raises
IndexError – The row or column is out of bound.
-
is_zero
()¶ Checks if all the elements have value 0.
-
is_zero_at
(row, column)¶ Check if the given element has value 0.
- Raises
IndexError – The row or column is out of bound.
-
nullspace
()¶ Returns an orthogonal matrix where the rows generate the nullspace of self.
Example
>>> from pyqec.sparse import BinaryMatrix >>> matrix = BinaryMatrix(4, [[0, 1, 2], [1, 2, 3]]) >>> matrix.nullspace() [1, 2] [0, 1, 3]
-
num_columns
()¶ Returns the number of columns in the matrix.
-
num_ones
()¶ Returns the number of elements with value 1.
-
num_rows
()¶ Returns the number of rows in the matrix.
-
num_zeros
()¶ Returns the number of elements with value 0.
-
rank
()¶ Computes the number of linearly independent rows (or columns) of the matrix.
Example
>>> from pyqec.sparse import BinaryMatrix >>> matrix = BinaryMatrix(4, [[0, 1, 2], [1, 3], [0, 2], [0, 2, 3]]) >>> matrix.rank() 3
-
row
(row)¶ Returns the given row as a BinaryVector.
- Raises
IndexError – The row is out of bound.
-
rows
()¶ >>> from pyqec.sparse import BinaryMatrix, to_dense >>> matrix = BinaryMatrix(3, [[0, 2], [1], [0, 1]]) >>> for row in matrix.rows(): ... print(row) [0, 2] [1] [0, 1]
-
shape
()¶ Returns a tuple of the numbers of rows and columns.
-
transposed
()¶ Returns the transpose of the matrix.
Example
>>> from pyqec.sparse import BinaryMatrix >>> matrix = BinaryMatrix(3, [[0, 2], [1], [0, 1]]) >>> matrix.transpose() [0, 2] [1, 2] [0]
-
vertical_concat_with
(other)¶ Returns the vertical concatenation of self and other matrix.
If the matrices have a different number of columns, the smallest one is padded with zeros.
Example
>>> from pyqec.sparse import BinaryMatrix >>> matrix = BinaryMatrix(4, [[0, 1, 2], [1, 2, 3]]) >>> matrix.vertical_concat_with(BinaryMatrix.identity(3)) [0, 1, 2] [1, 2, 3] [0] [1] [2]
-
static
zeros
(num_rows, num_columns)¶ A matrix filled with zeros.
Example
>>> from pyqec.sparse import BinaryMatrix, to_dense >>> matrix = BinaryMatrix.zeros(2, 3) >>> to_dense(matrix) array([[0, 0, 0], [0, 0, 0]], dtype=int32)
Binary vector¶
-
class
pyqec.sparse.
BinaryVector
¶ A sparse binary vector.
- Parameters
length (Int) – The number of elements in the vector. Must be a non-negative integer.
positions (Seq[Int]) – The positions of entries with value 1.
Example
>>> from pyqec.sparse import BinaryVector, to_dense >>> vector = BinaryVector(3, [0, 2]) >>> to_dense(vector) array([1, 0, 1], dtype=int32)
- Raises
ValueError – If the length is negative or if a position is out of bound.
-
bitwise_xor
(other)¶ Computes the bitwise xor sum of two vectors.
Example
>>> from pyqec.sparse import BinaryVector >>> left = BinaryVector(5, [0, 2, 4]) >>> right = BinaryVector(5, [1, 2, 3]) >>> left.bitwise_xor(right) [0, 1, 3, 4]
- Raises
ValueError – If the vectors have different lengths.
-
concat
(other)¶ Concatenates self with other.
Example
>>> from pyqec.sparse import BinaryVector >>> left = BinaryVector(5, [0, 2, 4]) >>> right = BinaryVector(4, [1, 3]) >>> left.concat(right) [0, 2, 4, 6, 8]
-
dot_with_matrix
(matrix)¶ Computes the dot product between self and a matrix.
This assume that the vector is in row shape and compute v * M.
Example
>>> from pyqec.sparse import BinaryVector, PyBinaryMatrix >>> vector = BinaryVector(3, [0, 2]) >>> matrix = PyBinaryMatrix(4, [[0, 3]], [0, 1, 2], [1, 3]]) >>> vector.dot_with_matrix(matrix) [0, 1]
- Raises
ValueError – If the vector length is the not the same as the matrix number of rows.
-
dot_with_vector
(other)¶ Computes the dot product between two vectors.
Example
>>> from pyqec.sparse import BinaryVector >>> left = BinaryVector(5, [0, 2, 4]) >>> right = BinaryVector(5, [1, 3]) >>> left.dot_with_vector(right) 0
- Raises
ValueError – If the vectors have different length.
-
element
(position)¶ Returns the value of the element at the given position.
- Raises
IndexError – The position is out of bound.
-
static
empty
()¶ Constructs a vector of length 0.
This is useful as a placeholder since it allocates a minimal amount of memory.
-
is_empty
()¶ Checks if the length of the vector is 0.
-
is_one_at
(position)¶ Checks if the element at the given position is one.
- Raises
IndexError – The position is out of bound.
-
is_zero
()¶ Checks if all elements are 0.
-
is_zero_at
(position)¶ Checks if the element at the given position is zero.
- Raises
IndexError – The position is out of bound.
-
len
()¶ Returns the number of elements in the vector.
-
non_trivial_position
(index)¶ Index the given value in the list of non-trivial positions.
Example
>>> from pyqec.sparse import BinaryVector >>> vector = BinaryVector(5, [0, 2, 4]) >>> vector.non_trivial_position(0) 0 >>> vector.non_trivial_position(1) 2 >>> vector.non_trivial_position(2) 4
- Raises
IndexError – The index is greater or equal to the weight.
-
weight
()¶ Returns the number of elements with value 1.
-
static
zeros
(length)¶ Constructs a vector of the given length filled with zeros.
Conversion to Numpy¶
-
pyqec.sparse.
to_dense
(sparse_bin_array)¶ Converts a sparse matrix or vector to a dense numpy representation.
- Parameters
sparse_bin_array (Union[BinaryMatrix, BinaryVector]) – The array to convert.
Example
>>> from pyqec.sparse import BinaryMatrix, to_dense >>> to_dense(BinaryMatrix.identity(3)) array([[1, 0, 0], [0, 1, 0], [0, 0, 1]], dtype=int32)
General operations¶
-
pyqec.sparse.
dot
(left, right)¶ Computes the dot product between two sparse binary arrays.
- Parameters
left (Union[BinaryMatrix, BinaryVector]) – The left hand side of the product.
right (Union[BinaryMatrix, BinaryVector]) – The right hand side of the product.
Examples
>>> from pyqec.sparse import BinaryMatrix, BinaryVector, dot >>> matrix1 = BinaryMatrix(3, [[0, 1], [1, 2]]) >>> matrix2 = BinaryMatrix(2, [[0], [1], [0, 1]]) >>> dot(matrix1, matrix2) [0, 1] [0] >>> vector = BinaryVector(3, [0, 2]) >>> dot(matrix1, vector) [0, 1] >>> dot(vector, matrix2) [1]