This document describes techniques that Web accessibility validation tools
may use to evaluate the conformance of HTML documents to the Web Content Accessibility
Guidelines 1.0 (WCAG 1.0). This document also describes techniques that
Web authoring tools may use to help authors modify HTML documents to conform
to WCAG 1.0. We anticipate that tool developers may develop accessibility
validation and/or repair modules to be incorporated into commercial authoring
tools, validation tools, and perhaps user agents.
This section describes the status of this document at the time of its
publication. Other documents may supersede this document. The latest status of
this document series is maintained at the W3C.
This is a W3C Working Draft produced by the Evaluation and Repair Tools Working
Group. The working group encourages
- feedback on existing techniques discussed in this document,
- suggestions for new techniques,
- implementation and testing of the techniques discussed in this
document.
The working group expects to collect and test new and existing techniques
in the next few months. The document will be updated to reflect the group's
findings.
Information about existing Evaluation, Repair, and Transformation Tools for
Web Content Accessibility is available from the working group's home page.
This is a draft document and may be updated, replaced, or obsoleted by
other documents at any time. It is inappropriate to use W3C Working Drafts as
reference material or to cite them as other than "work in progress". A list of
current W3C Recommendations and other technical documents can be found at http://www.w3.org/TR/.
Please send comments on this document to<EMAIL_ADDRESS>The archives for this
list are publicly available.
- Clean up all of the @@'s (open issues, questions and comments).
- Check for consistent language usage.
- Link to WCAG, AU and UA Techniques and EO Curriculum where
appropriate.
- Use WCAG notes or rationale as example language where possible or
appropriate.
- Inherit reference info between checkpoints from WCAG (e.g., at the end
of Checkpoint 10.1, "refer also to Checkpoint 12.4").
- Determine if we want to use "author" or "user." Then check for
consistent usage.
- Determine if we want to use "document" or "page." Then check for
consistent usage.
- Ensure that "Web" is capitalized consistently.
- Update and finish creating test files. Upload the images associated
with the test files.
- Resolve open issues both listed in this document as well as in the list of open
issues.
The Web Accessibility Initiative (WAI) has produced a foundation document,
The W3C Web Content
Accessibility Guidelines (WCAG 1.0), that describes what must be done to
make a Web page accessible to all. Tools are needed to help authors determine
if a web site is accessible to everyone and to help repair it if it is
not.
This document builds on the WCAG 1.0 foundation by outlining techniques
that evaluation and repair tools may use to uncover accessibility problems and
possibly repair them. These techniques may be used by those who create web
authoring tools or by anyone interested in creating accessible Web
documents.
It is important that people with disabilities are included in the "anyone
interested in creating accessible Web content." Creating accessible Web
content is as important as accessing Web content. Therefore, evaluation and
repair tools themselves need to be accessible to people with disabilities.
However, this document does not describe how to make the user interface
accessible. Please refer to the User
Agent Accessibility Guidelines for information on making the user
interface accessible.
Many people using evaluation and repair tools may be new to the Web and
will not be familiar with the various markup languages that are used. Many
others will not know about Web accessibility. Tools should be intuitive and
easy to use and available at a minimal cost. Tools should not generate
excessive warnings or false positive accessibility errors.
Some of the web-content accessibility checkpoints cannot be checked
successfully by software algorithms alone. There will still be a dependence on
the user's ability to exercise human judgment to determine conformance to the
guidelines. It is imperative that any tool have features that assist in
reminding, without nagging; in helping, without demeaning; in suggesting,
without demanding. We hope that the techniques in this document, implemented
in software programs, will gently guide authors along the path to more
accessible documents.
This document is based on The W3C Web Content Accessibility
Guidelines. It lists each guideline and checkpoint in in that document.
Under each checkpoint it lists one or more techniques for evaluating and, in
some cases, repair. �Each technique comprises the following subsections:
- Open issues for this technique
- This section lists open issues and questions about a particular
technique. �
- Evaluation:
- The algorithmic and heuristic tests that will be applied. consisting
of
- Elements - the elements to which this test
applies, e.g.
IMG
etc. If it only applies to an element
of a particular type, this is noted (e.g. INPUT
�TYPE="image"
>
- Requirements - the conditions which will be
tested for by means of algorithms and heuristics.
Note: in a few cases, the warning is always presented.
- Suggested message:
- Messages displayed to the author if the element is found and the
requirement is not satisfied.
- Suggested repair:
- Actions that may be required to repair the accessibility problem.
- Test files:
- Used to test evaluation tools to see if they find the accessibility
problem. These are under construction!!
- Discussion files:
- Discussion and comments on the technique.
Note. This document specifies only the function of
evaluation and repair tools. Nothing in this document should be taken to imply
a particular user interface.
Guideline 1. Provide equivalent
alternatives to auditory and visual content.
- Checkpoint 1.1 - Provide a text
equivalent for every non-text element
- Checkpoint 1.2 - Provide redundant
text links for each active region of a server-side image map
- Checkpoint 1.3 - Until user agents
can automatically read aloud the text equivalent of a visual track,
provide an auditory description of the important information of the visual
track of a multimedia presentation
- Checkpoint 1.4 - For any time-based
multimedia presentation (e.g., a movie or animation), synchronize
equivalent alternatives (e.g., captions or auditory descriptions of the
visual track) with the presentation
- Checkpoint 1.5 - Until user agents render
text equivalents for client-side image map links, provide redundant text
links for each active region of a client-side image map
Technique 1.1.1 [priority 1] Check
IMG
elements for valid "alt
" attribute
Open issues for this technique:
Evaluation:
- Element:
IMG
- Requirement: Valid "
alt
" attribute.
Valid "alt
" attribute:
- "
alt
" attribute must exist
- Not allowed - NULL "
alt
" value (alt=""
)
- Allowed - "
alt
" value of 1 or more spaces ("alt="
"
") but only if image is not within an "A
element
"
- Suspicious - "
alt
" attribute value could be file size (ends
with "bytes")
- Suspicious - "
alt
" attribute value ends with image file suffix.
- Suspicious - "
alt
" attribute value is placeholder text.
- Suspicious - "
alt
" attribute value is longer than 150
characters. Suggest that a description file be created.
Suggested message:
- Missing text equivalent: Missing text equivalent for image.
- Suspicious "
alt
" attribute: Suspicious text equivalent for
image: [current "alt
" text] - [could be file size | could be
file name | could be placeholder text | text equivalent should be short,
perhaps this could be a "longdesc
"].
- Invalid "
alt
" attribute: Invalid text equivalent for image:
[text equivalents can not be empty].
Suggested repair:
- Prompt the user for a text equivalent for the image.
- If the document contains another instance of the image and that image
contains an "
alt
" attribute, suggest that "alt
"
attribute value.
- If the image is assumed to be a bullet,
suggested text should be "bullet".
- If the image is assumed to be a horizontal
rule, suggested text should be "horizontal rule".
- Other suggestions by
Daniel Dardailler
- Suggestions by
Michael Vorburger
- After user has entered an
"alt"
attribute for the image,
check the site for other instances of the image. If the site contains
other images that are the same and they do not have a text equivalent,
suggest that all same images without an "alt
" attribute use
the new "alt
" attribute value.
Test Files and Discussion Files:
Technique 1.1.2 [priority 1] Verify
that valid IMG
element descriptions ("longdesc"
attribute or d-link) are provided where necessary.
Open issues for this technique:
- Daniel D. on May 19, 1999 suggested that we could check for the
complexity of the image by looking for a "
caption
"
attribute.
- Element:
IMG
- Requirements:
- Valid "
longdesc
" attribute or a d-link required if
describing the image will add information not given in the text of the
page. The amount of information in the image and the context in which
it is used will determine how detailed the description should be.
Note: d-link now deprecated.
- Cases where a description is not required:
Valid "longdesc
" attribute:
- If describing the image will add information not given in the text of
the page, you need to provide a description of the image. The amount of
information in the image and the context in which it is used will
determine how detailed the description should be.
- Ask user if the image presents information that is not included in the
page or in the text equivalent for the image. Allow the user to create or
associate a description.
- with the "
longdesc
" attribute on an IMG
element
- via a D-link
- If another document on the same site uses the same image and has a
"
longdesc
", suggest that "longdesc
" file.
Technique 1.1.3 [priority 1] Check
INPUT
elements of type="image"
for valid
"alt
" attribute
- Element:
INPUT type="image"
- Requirement: Valid "
alt
" attribute.
Valid "alt
" attribute:
- "
alt
" attribute must exist
- Not valid - NULL "
alt
" value (alt=""
)
- Not valid - "
alt
" value of 1 or more spaces (alt="
"
)
- Suspicious - "
alt
" attribute value could be file size (ends
with "bytes")
- Suspicious - "
alt
" attribute value ends with image file suffix.
- Suspicious - "
alt
" attribute value is placeholder text.
- Missing text equivalent: Missing text equivalent for this button.
- Suspicious text equivalent: Suspicious text equivalent for button:
[current "
alt
" attribute] - [could be file size | could be
file name | could be placeholder text].
- Invalid text equivalent: Invalid text equivalent for button: [
"
alt
" attribute can not be empty | text equivalent can not
contain only 'spaces'].
- Prompt the user for text equivalent.
- If another document on the same site has an INPUT element with the same
TYPE value, suggest that type value.
Technique 1.1.4 [priority 1] Check
APPLET
elements for valid HTML equivalent
- Element:
APPLET
- Requirements:
- Valid "
alt
" attribute OR
- accessible �HTML within
APPLET
element
Valid "alt"
attribute values:
- Not allowed - NULL "
alt
" attribute value
(alt=""
)
- Not allowed - "
alt
" attribute value of 1 or more spaces
(alt=" "
)
- Suspicious - "
alt
" attribute value could be file size (ends
with "bytes")
- Suspicious - "
alt
" attribute value ends with image file suffix.
- Suspicious - "
alt
" attribute value is placeholder alt-text text.
- Suspicious - "
alt
" attribute ends with applet executable suffix.
- Allowed - no "
alt
" attribute if text is provided within the
content of the APPLET
element.
- Missing text equivalent: Applet must have valid a valid
"
alt
" attribute or accessible HTML content."
- Suspicious text equivalent: Suspicious text equivalent for applet:
[current "
alt
" attribute value] - [could be file size | could
be image file name | could be placeholder text | could be applet
executable name].
- Invalid text equivalent: Invalid "
alt
" attribute for applet
- [text equivalent can not be empty | text equivalent can not be all
'spaces'].
- Prompt the user for text equivalent.
- If the same applet is used on the same site and has an
"
alt
" attribute, suggest that "alt
" attribute
value.
Technique 1.1.5 [priority 1] Check
OBJECT
elements of
type="
image_MIME_types
"
for
valid text equivalents and descriptions (where necessary)
Open issues for this technique:
- This only covers text equivalents. Where is non-text covered if not
here?
- Element:
OBJECT
- Requirement: Between
OBJECT
start element and
OBJECT
end element must be a valid alternative representation
element.
Valid alternative representation element:
- Missing alternative representation: Missing alternative representation
for this object.
- Suspicious alternative representation: Suspicious alternative
representation for this object: [current alternative representation] -
[could be placeholder text]
- Prompt user for new alternative representation.
- If the site contains a document that contains the same object and that
object contains a valid alternative representation, suggest that
alternative representation.
Test file - OBJECT
text equivalent.
Technique 1.1.6 [priority 1] Verify that
text equivalents are provided for linked audio files where
necessary
- Elements:
A href=soundFile
- Requirement: Audio file must be described within the document or
document must contain a link to a text equivalent file.
- Audio files require a text equivalent. Is there an associated text
equivalent for this audio file: [audio file name]?
- Prompt user for text transcript of audio file.
Test file - text for
sound files.
Technique 1.1.7 [priority 1]
Verify that text equivalents are provided for embedded audio files
where necessary
Evaluation:
- Elements:
OBJECT
type=Audio_or_Video_MIME_type
- Requirement: Audio file must be described within the document or
document must contain a link to a text equivalent file.
- Audio and video files require a text equivalent. Is there an associated
text equivalent for this audio/video file: [audio/video file name]?
- Prompt user for text transcript of audio/video file and embed it between
start and end tag.
Technique 1.1.8 [priority 1] Check
FRAME
elements for valid "longdesc
" attribute
- Element:
FRAME
- Requirement: Valid "
longdesc
" attribute (refer to
checkpoint 12.1 for information about titling frames).
- If a
FRAMESET
has three or more frames and at least one of
the frames does not have a "longdesc
" attribute, ask the user
if the relationships between frames are not apparent in the titles for
each frame.
Valid "longdesc
" attribute:
- Must not be NULL
- Must be a valid URI
- The file pointed to by the URI must be accessible HTML
- Missing "
longdesc
": Missing description for this
frame.
- Invalid "
longdesc
" URI: Invalid 'long description' file
name for this frameset: [current "longdesc
" URI] - [can not
be empty].
- If the relationships between frames are not obvious then ask that they
provide a description of the relationships. Allow the user to create a
"
longdesc
" file or associate an existing
"longdesc
" file. It is suggested that each FRAME
in the reference the same "longdesc
" as the description of
the relationships should be available from each FRAME
.
Technique 1.1.9 [priority 1] Check
AREA
elements for valid "alt
" attribute
- Element:
AREA
- Requirement: Elements must have a valid "
alt
"
attribute.
Valid "alt
" attribute:
- Not allowed - NULL "
alt
" value (alt=""
)
- Suspicious - "
alt
" attribute value is placeholder text.
- @@is this complete?
- Missing text equivalent: Missing text equivalent for this image map
area.
- Suspicious "
alt
": Suspicious "alt
" attribute
for this image map area: [current alt text].
Prompt user for "alt
" text for the AREA
element.
Technique 1.1.10 [priority 1] Check
SCRIPT
elements for valid equivalents where necessary
- Element:
SCRIPT
- Requirements:
NOSCRIPT
section must follow the SCRIPT
end element AND
NOSCRIPT
section must contain Accessible HTML
NOSCRIPT
section must not contain placeholder text
Suggested message:
- Language for missing
NOSCRIPT
: Missing
NOSCRIPT
element for this SCRIPT
element.
- If contained HTML not accessible:
NOSCRIPT
section contains
inaccessible HTML: [description of problems].
- Insert
NOSCRIPT
section
- Allow user to insert text or link to text equivalent file that describes
the
SCRIPT
@@handled by technique 13.1.1 - verify that targets are clearly identified?
What else do we need to check for?
Technique 1.1.12 [priority 1] Verify that valid
text equivalents are provided for PRE
and XMP
elements used to create ASCII art.
Open issues for this technique:
- A-Prompt has been using an algorithm to detect ASCII art (There must be
5 or more lines of text and there must be 5 or more same characters in a
sequence). This works quite well but detects things such as code samples
(don't require text equiv.) and guitar tabulature (do require text equiv.)
Should we suggest this algorithm in the evaluation?
- What about ASCII art that is interspersed in text, such as in
P
elements?
- Bill Shackleton suggested that a tool use a library of well-known ascii
art to detect some ascii art such as emoticons. Yahoo
maintains a list of ascii art one list is specifically about smileys.
- Elements:
PRE
and XMP
- Requirement: ASCII art has an associated text equivalent.
- Character based artwork (ASCII art) requires a textual description.
- Ask user for a description of the ASCII art or allow them to add a link
to a text equivalent file.
Technique 1.2.1 [priority 1] Verify
that a server-side image map has associated text links.
Open issues for this technique:
- WCAG issue: text links are a priority 3 if the same image also has a
client side map (images can have both a client-side and a
server-side).
- Element:
IMG ISMAP
- Requirement: text link for each active area of the image map
- Server-side image maps should have associated text links in the
document.
- Prompt the user for associated text links OR
- help the user convert the server-side image map to a client-side image
map and provide text-equivalents for each link in the client-side image
map.
- If possible, check the text links against the links contained on the
server-side image map by
- asking user to upload the server side definition file if it's a
standard format or
- pinging the image map with random coordinates and seeing if all
returned pages correspond to the links.
Technique 1.3.1 [priority 1]
Verify that multimedia have audio descriptions.
- Elements:
any_tag
any_attribute=multimedia_uri
,
OBJECT
type=
any_multimedia_type
- Requirement: Multimedia presentations should have an associated audio
description.
- Display the multimedia file and allow the user to create an audio
description of the important information.
- Allow the user to add a link to an existing audio description file.
Checkpoint 1.4 - For any time-based
multimedia presentation (e.g., a movie or animation), synchronize equivalent
alternatives (e.g., captions or auditory descriptions of the visual track)
with the presentation
Technique 1.4.1 [priority 1]
Verify that multimedia have synchronized equivalents.
- Elements:
any_tag any_attribute=multimedia_uri
,
OBJECT
type=
any_multimedia_type
- Requirement: Multimedia presentations should have synchronized
equivalents.
- For any time-based multimedia presentation (e.g., a movie or animation),
synchronize equivalent alternatives
- Give user option to edit option with editor of their choice (e.g. the
default editor on their system)
Open issues for this technique:
- This technique is a specific example of 1.4.1. Should it stand on its
own or be incorporated into 1.4.1?
- This technique is also SMIL specific while the majority of techniques
are HTML specific. Should we include a SMIL specific technique?
- SMIL Elements:
- Requirement: SMIL files should have the
system-captions
flag for at least one text stream and one auditory stream.
Checkpoint 1.5 - Until user agents render text
equivalents for client-side image map links, provide redundant text links for
each active region of a client-side image map
Technique 1.5.1 [priority 3] Verify
that text links are provided for client-side image maps.
- Element:
IMG usemap
- Requirement: Document must contain text links for each active area of
the image map.
- Associated text links may be found by searching the document for anchors
with
href
attribute values that correspond to the
AREA
elements in the given usemap
.
- Client-side image maps should have associated text links.
- Allow the user to create associated text links for each active area in
the image map.
Guideline 2. Don't rely on color alone.
- Checkpoint 2.1 - Ensure that all information
conveyed with color is also available without color, for example from
context or markup
- Checkpoint 2.2 - Ensure that foreground
and background color combinations provide sufficient contrast when viewed
by someone having color deficits or when viewed on a black and white
screen
Checkpoint 2.1 - Ensure that all information
conveyed with color is also available without color, for example from context
or markup
Technique 2.1.1 [priority 1] Verify that
information conveyed with color is available without color
- Elements:
IMG |
APPLET |
OBJECT |
SCRIPT |
INPUT |
as well as the HTML
elements and attributes listed in the next technique (2.2.1).
- Ensure that information is not conveyed through color alone. For
example, when asking for input from users, do not write "Please select an
item from those listed in green." Instead, ensure that information is
available through other style effects (e.g., a font effect) and through
context (e.g,. comprehensive text links).
- Display a user notification if any of the color-possible elements are in
the document.
Checkpoint 2.2 - Ensure that foreground and
background color combinations provide sufficient contrast when viewed by
someone having color deficits or when viewed on a black and white screen
Technique 2.2.1 [priority 3] Test the
color attributes of the following elements for visibility:
- Elements:
BODY bgcolor | text | alink | link | vlink | background
=
anything
�OR
TABLE bordercolor | bgcolor
=
anything
�OR
TD | TH � �bgcolor
=
anything
OR
HR color =
anything
OR
any_element
style="
any_color_specification
"
STYLE "any_color_specification"... STYLE
- Where any_color_specification is defined as any CSS
specification which contains:
color | background-color | background-image |
background
- Requirement: Determine color visibility.@@needs work?
Ideally, images and multimedia object should also be tested for color
visibility but algorithms are beyond the scope of this specification.
Color visibility can be determined according to the following
algorithm:
(This is a suggested algorithm that is still open to
change.)
Two colors provide good color visibility if the brightness difference and
the color difference between the two colors are greater than a set range.
Color brightness is determined by the following formula:
((Red value X 299) + (Green value X 587) + (Blue value X 114)) / 1000
Note: This algorithm is taken from a formula for converting RGB values to YIQ
values. This brightness value gives a perceived brightness for a color.
Color difference is determined by the following formula:
(maximum (Red value 1, Red value 2) - minimum (Red value 1, Red value 2)) +
(maximum (Green value 1, Green value 2) - minimum (Green value 1, Green value
2)) + (maximum (Blue value 1, Blue value 2) - minimum (Blue value 1, Blue
value 2))
The rage for color brightness difference is 125. The range for color
difference is 500.
- Poor visibility between text and background colors.
- Allow the user to change the poor color combinations.
- Store any good color combinations entered by the user and use them as
default prompts in the future.
Guideline 3. Use markup and style
sheets and do so properly
- Checkpoint 3.1 - When an appropriate markup
language exists, use markup rather than images to convey information
- Checkpoint 3.2 - Create documents that validate
to published formal grammars
- Checkpoint 3.3 - Use style sheets to
control layout and presentation
- Checkpoint 3.4 - Use relative rather than
absolute units in markup language attribute values and style sheet
property values
- Checkpoint 3.5 - Use header elements to
convey document structure and use them according to specification
- Checkpoint 3.6 - Mark up lists and list
items properly
- Checkpoint 3.7 - Mark up quotations. Do not use
quotation markup for formatting effects such as indentation
Checkpoint 3.1 - When an appropriate markup
language exists, use markup rather than images to convey information
Technique 3.1.1 [priority 2] Verify that
elements do not need to be converted to an appropriate markup language.
- Elements:
PRE | IMG | OBJECT | APPLET
- When an appropriate markup language exists, use markup rather than
images to convey information. For example, use MathML to mark up
mathematical equations, and style sheets to format text and control
layout
- Display a user notification if any of these possible conversion elements
are in the document.
- Help authors convert decorative ASCII art in
PRE
elements
to SVG or an image format.
- Help authors convert ASCII art representing tables of data in PRE
elements to TABLE elements.
- Help authors convert images (
IMG
or OBJECT
)
used to format text to XHTML/XML with style sheets.
- Help authors convert images (
IMG
or OBJECT
)
used to format mathematical equations to MathML.
Checkpoint 3.2 - Create documents that validate to
published formal grammars
Technique 3.2.1 [priority 2] Check document
for public text identifier
- Reference BizTalk and OASIS catalogs?
- Element: none �(i.e. applies to all documents)
- Requirements:
- If no
!DOCTYPE
at all: Missing language identifier for this
document.
- If document type is defined in HTML element: "Document type should be in
the document type definition. �It's use in the HTML element is
deprecated.
- If the document type is in the HTML element: move to the
!DOCTYPE
declaration.
- If no valid document type at all: Prompt the user for a public text
identifier, preferably by offering a menu of choices and explanations
Checkpoint 3.3 - Use style sheets to control
layout and presentation
Technique 3.3.1 [priority 2] Check document for
use of style sheets.
- Elements: none (i.e. applies to all documents)
- Requirements: Document should contain at least one of the
following:
STYLE
or LINK rel="stylesheet"
elements within the HEAD
element | "style
"
attributes on any element | FONT
| BASEFONT
|
"text," "vlink," "link," and "alink"
attributes on
BODY
.
- If layout tables are identified (see technique 5.1.1), trigger this
check as well. We will inform user that style sheets can be used instead
of layout tables in 5.1.1.
- Use style sheets to control layout and presentation. For example, use
the CSS '
font
' property instead of the HTML FONT
and BASEFONT
elements to control font styles
- If style sheets are not used, verify that the author has chosen not to
modify the presentation in any way.
- If
FONT
or BASEFONT
elements or "text,"
"vlink," "link," and "alink"
attributes on BODY
,
suggest or help the author convert the presentation properties to style
sheets.
- If the author chooses to convert deprecated markup to style sheets or
add style sheets, trigger technique 6.1 to verify that the document is
readable when style sheets are not applied.
Checkpoint 3.4 - Use relative rather than
absolute units in markup language attribute values and style sheet property
values
Technique 3.4.1 [priority 2] Check
document for relative units of measure.
- Elements:
- "
style
" attribute on any element OR
STYLE
- Requirements For any HTML or CSS element defined to take a
%LENGTH, %PIXELS, %MULTILENGTH
, or
%MULTILENGTHS
, a validated value should either end with "%"
or begin with "+" or "-" or use the "em" or "ex" units.
- Exception: "
width
" and "height
" attributes of
IMG, OBJECT, and APPLET
elements.
- This element uses absolute units of measure rather than relative units
of measure.
- Allow user to change the units of measure as follows:
- Allow user to specify which of the absolute sizes is the
default
- Automatically compute all others in terms of the default, with
choice of %, +/-, or em/ex �
Checkpoint 3.5 - Use header elements to
convey document structure and use them according to specification
Technique 3.5.1 [priority 2] Check document
for header nesting
- Elements:
Header
elements (H1-H6)
- Requirements: Header elements should nest according to the following
rules
- Header levels must not increase by more than 1 level. Example: H2
following H1 is good. H3 following H1 is bad.
- Header elements can decrease by any level. Example: H2 following H5
is OK.
- Improper header nesting: Header levels must not increase by more than
one level per heading. Do not use headings to create font effects; use
style sheets to change font styles.
- Allow user to modify the header numbering within the document.
Technique 3.5.2 [priority 2] Check document
for missing header markup
- Element:
P
- Requirement: Paragraphs should be verified that they are not headings.
Potential headings can be identified by:
- Text elements occur within a paragraph AND
- The paragraph is less than 10 words AND
- The paragraph contains only text items or formatting elements
AND
- All text in the paragraph is formatted as bold and/or italics and/or
underline.
- Text has been identified that could possibly be a header. Is this text
used as a header: [potential header text]?
- Allow user to convert the text to a header.
Technique 3.5.3 [priority 2] Verify
that header elements are not used for formatting.
- Elements:
Header
elements (H1- H6)
- Requirement: If a header element's text content is longer than 20 words,
query the user.
- Header elements (H1 - H6) should be used to define headers and should
not be used for formatting text.
- Allow the user to convert any header text to another type. Possible
types are:
- Paragraph
- Blockquote
Checkpoint 3.6 - Mark up lists and list items
properly
- Elements:
- Requirements
- Each
UL/OL/DL
tag must be followed by at least one
LI
. (This avoids the use of lists to create formatting
e.g. via UL UL UL...
)
- Suspicious: a single
LI
, which may be used merely for
formatting
- List items should not be used for formatting text. Use Style sheets or
tables for formatting text.
- Allow the user to format the text within the LI element to another
element via �a choice of
Checkpoint 3.7 - Mark up quotations. Do not use
quotation markup for formatting effects such as indentation
Technique 3.7.1 [priority 2] Verify instances
where quote markup should be used.
Q
is not supported in today's browsers, thus converting
quotes marks to Q
will basically delete the quote marks for
all users. what do we suggest in the meantime?
- Element:
P
[list of others?] elements
- Requirement: quote should be marked up with
Q
or
BLOCKQUOTE
. Potential quotes can be identified by:
- Any text that is enclosed by quote marks (" " or ' ').
- Indented text.
- Lots of emphasized text (greater than x words??@@)
- The following text may need to be marked using
Q
or
BLOCKQUOTE
: [potential quote text].
- Allow the user to convert blocks of text to
Q
or
BLOCKQUOTE
.
Technique 3.7.2 [priority 2] Verify that
Q
and BLOCKQUOTE
are used properly
- Elements:
Q
and BLOCKQUOTE
- Requirement:
- Inline quotes (marked with
Q
) have at least one word in
front of, or behind, the quote text and are less than 10 words
- Long quotes (marked with
BLOCKQUOTE
) are greater than
10 words.
- If a block of text is marked as
BLOCKQUOTE
when it should
be marked as Q
: This text should be marked as Q
not BLOCKQUOTE
: [quote text].
- If a block of text is marked as
Q
when it should be marked
as BLOCKQUOTE
: This text should be marked as
BLOCKQUOTE
not Q
: [quote text].
- Allow the user to convert blocks of text to
Q
or
BLOCKQUOTE
or vice versa.
Technique 3.7.3 [priority 2] Verify that
BLOCKQUOTE
is not used for formatting
- Element:
BLOCKQUOTE
unless text content has quote marks (""
or '').
- Requirement:
- Not allowed: nested
BLOCKQUOTE
s.
- This text should be marked as normal text but formatted using style
sheets or a table.
BLOCKQUOTE
elements should be used to define quotes and
should not be used for formatting text.
- Allow the user to transform the text in the
BLOCKQUOTE
element into a P
(paragraph) element.
- Checkpoint 4.1 - Clearly identify changes in the
natural language of a document's text and any text equivalents (e.g.,
captions)
- Checkpoint 4.2 - Specify the expansion of
each abbreviation or acronym in a document where it first occurs
- Checkpoint 4.3 - Identify the primary
natural language of a document
Checkpoint 4.1 - Clearly identify changes in the
natural language of a document's text and any text equivalents (e.g.,
captions)
- Element: none (i.e. applies to all documents that contain text)
- Requirement: The document must contain at least 3 words of text.
- Any words or phrases in a document that are not in the primary language
of the document should be identified.
- Display the above user notification and provide the following
suggestions:
- For blocks of text that are not in the primary language and are
already enclosed by markup elements such as
P
aragraph,
DIV
or EM
, set the "lang
"
attribute of the markup element.
- For words or phrases that are not in the primary language, enclose
them with a
SPAN
element and set the SPAN
element's "lang
" attribute.
- Ensure that all captions and other text equivalents are
checked.
Checkpoint 4.2 - Specify the expansion of each
abbreviation or acronym in a document where it first occurs
Technique 4.2.1 [priority 3] Verify that
abbreviations and acronyms need expanding.
- Elements: none (i.e. applies to all documents that contain text)
- Requirements:
- Document must contain at least 3 words.
- Document contains a potential abbreviation or acronym.
Potential abbreviation:
- Any word greater than 2 characters that is all capital letters
Potential acronym:
- Any word that starts with a capital letter, contains lower case
characters and ends with a period.
- A potential acronym/abbreviation has been discovered: [potential
acronym/abbreviation].
- Ask the user if the acronym or abbreviation was defined elsewhere on the
page and if so give the user the option to re-use it.
- Allow the user to enter a definition for the abbreviation of
acronym.
Checkpoint 4.3 - Identify the primary natural
language of a document
Technique 4.3.1 [priority 3] Verify the primary
language of the document
- Element:
HTML
- Requirements: Must contain a valid "
lang
" attribute
Valid "lang
" attribute:
- Missing "
lang
" attribute: The primary language of this
document has not been set.
- Invalid "
lang
" attribute: The primary language of this
document is invalid.
- Prompt the user for the primary language of the document.
- Ensure that the language entered is one of the ISO 639 language
codes.
- A (somewhat costly) technique for guessing the primary language, is to
check for the use of common words in a language. For example, if you find
"a, the, you, for, is, of, and" then it's English. If you find "le, du,
la, a, se, pour, aux, des, ne" then it's French, etc.
- Checkpoint 5.1 - For data tables, identify
row and column headers
- Checkpoint 5.2 - For data tables that
have two or more logical levels of row or column headers, use markup to
associate data cells and header cells
- Checkpoint 5.3 - Do not use tables
for layout unless the table makes sense when linearized
- Checkpoint 5.4 - If a table is used for
layout, do not use any structural markup for the purpose of visual
formatting
- Checkpoint 5.5 - Provide summaries for
tables
- Checkpoint 5.6 - Provide abbreviations
for header labels
Checkpoint 5.1 - For data tables, identify row
and column headers
Technique 5.1.1 Determine the purpose of the
table
The purpose of the table must be determined before performing an
accessibility evaluation. To help the author make this assessment, the
following language may be used:
- Data tables present relational data such as a bus schedule, a comparison
of regional sales figures, or a listing of employee contact information.
Cells in data tables are related to each other and usually must be
perceived as a group.
- Layout tables visually format images, text, and other information on the
page such as a navigation bar, or a newspaper page with stories, links,
and images. Each cell in a layout table is normally independent and can be
viewed on its own.
Technique 5.1.2 [priority 1] Check data
table for row and column headers
- Element:
TABLE
.
- Requirement: the table must have at least one complete row of headers or
one complete column of headers.
- This technique applies only to tables used for data, not to tables used
for layout purposes.
- If both row and column headers are missing: Table is missing
headers.
- If either row or column headers are missing: Table has row/column
headers but may require column/row headers.
- Allow the user to modify the table to include row headers and/or column
headers.
- Allow the user to convert the top row and/or the left column to
headers.
- The user should create at least one complete row or one complete column
of headers.
Checkpoint 5.2 - For data tables that have
two or more logical levels of row or column headers, use markup to associate
data cells and header cells
Technique 5.2.1 - [Priority 1] Check data
tables for multiple levels of row and column headers
- Element:
TH span=(2 or more)
�and either
- two or more
TR
elements containing at least one
TH
- two or more
TH
elements within any TR
- Requirements:
- use of
SCOPE | AXIS | HEADER
- two or more rows containing
TH
OR �
- two or more columns contain
TH
- Your table should identify structural groups of rows and groups of
columns. Label table elements with the "
scope
",
"headers
", and "axis
" attributes so that future
browsers and assistive technologies will be able to select data from your
table by filtering on categories.
- If the table does contain 2 or more logical levels of row or column
headers, use the HTML 4
table algorithm to show the author how the headers are currently
associated with the cells. If the author determines that the current
mark-up is not sufficient, allow the author to markup the table
TD
or TH
elements with scope
,
axis
, or headers
attributes.
Checkpoint 5.3 - Do not use tables
for layout unless the table makes sense when linearized
Technique 5.3.1 [priority 2] Verify that
layout tables make sense when linearized
- Element:
TABLE
- Requirement: Layout tables should make sense when linearized. This
technique applies only to tables used for layout purposes, not to data
tables.
- Tables used for layout should make sense when linearized.
- When a table is 'linearized,' the cells are read in the order in which
they appear in the HTML source.
- Linearize the table and ask the author to verify that the result is
understandable.
Checkpoint 5.4 - If a table is used for layout,
do not use any structural markup for the purpose of visual formatting
Technique 5.4.1 [priority 2] Check layout
tables for structural markup
- Element:
TABLE
- Requirements: Contains at least one
TH
element. This
technique applies only to tables used for layout purposes, not to data
tables.
- Tables used for layout should not use table headings to create
formatting effects.
- Allow user to change appearance of
TH
cells by
- style sheet properties
EM
and/or STRONG
Checkpoint 5.5 - Provide summaries for
tables
Technique 5.5.1 [priority 3] Check
TABLE
elements for valid "summary
" attribute
- Element:
TABLE
- Requirement: Must have valid "
summary
" attribute.
- If the table has nested headings, cells that span multiple columns or
rows, or other relationships that may not be obvious from analyzing the
structure of the table but that may be apparent in a visual rendering of
the table, a valid "
summary
" attribute may be provided.
Valid "summary
" attribute:
- For missing summary - "Table is missing a summary." "In the summary,
describe the purpose of the table (either layout or data). For example
''This table charts the number of cups of coffee consumed by each senator,
the type of coffee (decaf or regular), and whether taken with sugar.
- Additional help text: A summary of the relationships among cells is
especially important for tables with nested headings, cells that span
multiple columns or rows, or other relationships that may not be obvious
from analyzing the structure of the table but that may be apparent in a
visual rendering of the table. A summary may also describe how the table
fits into the context of the current document. If no caption is provided,
it is even more critical to provide a summary.
- Allow the user to enter a summary of the table.
Technique 5.5.2 [priority 2] Check TABLE
elements for valid
CAPTION
element.
Evaluation:
- Element:
TABLE
- Requirement: @@
Suggested message:
- This table does not have a caption: A table caption describes the nature
of the table in one to three sentences. For example, "Cups of coffee
consumed by each senator."
Suggested repair:
- Allow the author to enter a CAPTION
Checkpoint 5.6 - Provide abbreviations for
header labels
Technique 5.6.1 [priority 3] Check table
for header abbreviations
- How determine if an abbreviation is pronounceable? ASCII characters
only?
- Element:
TH
- Requirement: Valid "
abbr
" attribute if the header name is
greater than 15 characters.
Valid "abbr
" attributes:
- Not allowed - NULL "
abbr
" value ("")
- Not allowed - "
abbr
" value of spaces (" ")
- Suspicious - placeholder "
abbr
"
values
- "
abbr
" values should be shorter than 15 characters, but
still pronounceable.
- Table header is missing an abbreviation.
- Allow user to enter abbreviations for table header elements.
Guideline 6. Ensure that pages featuring
new technologies transform gracefully
- Checkpoint 6.1 - Organize
documents so they may be read without style sheets
- Checkpoint 6.2 - Ensure that
equivalents for dynamic content are updated when the dynamic content
changes
- Checkpoint 6.3 - Ensure that pages are usable
when scripts, applets, or other programmatic objects are turned off or not
supported
- Checkpoint 6.4 - For scripts and
applets, ensure that event handlers are input device-independent
- Checkpoint 6.5 - Ensure that dynamic
content is accessible or provide an alternative presentation or page
Checkpoint 6.1 - Organize documents
so they may be read without style sheets
Technique 6.1.1 [priority 1] Verify that
the document is readable when style sheets are not applied.
- Elements:
LINK rel="stylesheet"
STYLE
- At least one "
style
" attribute used on any
element.
Suggested message:
- Ensure this document can be read without style sheets.
Suggested repair:
- Display a user notification if any use of style sheets is detected.
Checkpoint 6.2 - Ensure that equivalents
for dynamic content are updated when the dynamic content changes
Technique 6.2.1 [priority 1] Check the
source of FRAME
and IFRAME
elements for valid markup
files.
- Elements:
FRAME
or IFRAME
- Requirements:
- Valid "
src
" attribute values must have a suffix of
".htm," ".html," ".shtm," ".shtml," ".cfm," ".cfml," ".asp," ".cgi,"
".pl", ".smil" or target document must have a known public identifier
at the top of file.
- Frame source: [frame source file name] is not a valid markup file.
- Create an HTML "wrapper" around known object types, e.g. if the target
is an image, place the image in an HTML file.
- @@Adjust Javascript to point inside the wrapper?
Technique 6.2.2 [priority 1] Verify
that equivalents of dynamic content are updated and available as often as the
dynamic content.
Open issues for this technique:
- This is similar to issues related to Guideline 7. do we need to tie them
together in some way?
- Elements:
SCRIPT,
APPLET, OBJECT
�type=@@?
, any_element �event_attribute where
event_attribute is "onmouseover" etc.
- Requirements: any actions that change the display must change the
equivalent @@Is this computable in a practical time (cf. NP complete) .
�Computer science help needed here. �Of course, as in other parts of
document, the fact that the equivalent changes is no guarantee that
equivalent is correct than it is guaranteed that
"alt"
text
for an image is correct.
- Ensure that the descriptions of dynamic content are updated with changes
in the dynamic content.
Checkpoint 6.3 - Ensure that pages are usable when
scripts, applets, or other programmatic objects are turned off or not
supported
Technique 6.3.1 [priority 1]
Verify that the page is usable when programmatic objects are disabled.
- Elements:
SCRIPT, OBJECT type=@@?, EMBED, APPLET
- Requirements:
- existence of "
alt
" and/or "title"
and/OR
- accessible alternative content in the body of
OBJECT,
NOSCRIPT, NOEMBED, or APPLET
.
- Ensure that pages are usable when scripts, applets, or other
programmatic objects are turned off or not supported.
- Provide means to create an accessible alternative representation or
provide a link to one.
Checkpoint 6.4 - For scripts and
applets, ensure that event handlers are input device-independent
Technique 6.4.1 [priority 2]
Check for device independent event handlers.
- Elements:
SCRIPT, OBJECT �type=@@?, EMBED, APPLET
- Requirements: Objects must not contain device dependent event handlers.
@@Does this mean checking Java, Flash, etc? Can we only do this for
scripting? Or prompt the author to check?
- For scripts and applets, ensure that event handlers are input
device-independent.
- Display object source code and suggest device independent replacement
code.
Checkpoint 6.5 - Ensure that dynamic content
is accessible or provide an alternative presentation or page
Technique 6.5.1 [priority 2] Check that
a NOFRAMES
element exists within each FRAMESET
.
- Element:
FRAMESET
- Requirements:
- A valid
NOFRAMES
section should exist within each
FRAMESET
section
Valid NOFRAMES
section
- Must contain at least one word of text or accessible HTML code.
- The contents of the
NOFRAMES
element must provide the
necessary links to navigate the site.
- Not allowed: Telling the user that they should upgrade to a browser that
supports frames. Suspicious words within the text of a
NOFRAMES
element: "upgrade," "full advantage," supports
frames," "missing" etc.
- Does your page work if frames are not loaded?
- Allow user to construct a valid
NOFRAMES
section.
@@ is this covered by 6.3.1 (Verify that the page is usable when
programmatic objects are disabled)?
Guideline 7. Ensure user control of time-sensitive
content changes
- Checkpoint 7.1 - Until user agents allow
users to control flickering, avoid causing the screen to flicker.
- Checkpoint 7.2 - Until user agents allow users
to control blinking, avoid causing content to blink
- Checkpoint 7.3 - Until user agents
allow users to freeze moving content, avoid movement in pages
- Checkpoint 7.4 - Until user agents
provide the ability to stop the refresh, do not create periodically
auto-refreshing pages
- Checkpoint 7.5 - Until user agents
provide the ability to stop auto-redirect, do not use markup to redirect
pages automatically
Checkpoint 7.1 - Until user agents allow users
to control flickering, avoid causing the screen to flicker
Technique 7.1.1 [priority 1] Verify that the page
does not cause flicker.
- It is desirable that a tool be able to measure flicker. This could be
done by software that renders, takes screenshots and compares. [Len
Kasday, 23 January 2000]
- Elements:
SCRIPT
OBJECT type =
(@@what are the type attribute values
for Java, etc.?)
EMBED
APPLET
IMG
element with "src
" name ending with
'.gif'.
Suggested message:
- Display flicker is distracting and may be dangerous to some users.
Please ensure this element does not cause the display to flicker.
Suggested repair:
- Display the object and allow the user to verify that it does not cause
display flicker. If object does cause flicker, allow user to modify
object.
Checkpoint 7.2 - Until user agents allow users to
control blinking, avoid causing content to blink
Technique 7.2.1 [priority 1] Check for
BLINK
elements
- The
BLINK
element is not defined in any W3C HTML
specification and should not be used.
- Allow the user to remove
BLINK
elements from the
document.
- Allow the user to replace
BLINK
elements with any of the
following elements:
STRONG
EM
SPAN
- allow the user to enter attributes for the
element.
H1
H2
H3
H4
H5
H6
Checkpoint 7.3 - Until user agents allow
users to freeze moving content, avoid movement in pages
Technique 7.3.1 [priority 1] Check for
MARQUEE
elements
- The
MARQUEE
element is not defined in any W3C HTML
specification and should not be used.
- Allow the user to remove
MARQUEE
elements from the
document.
- Allow the user to replace
MARQUEE
elements with any of the
following elements:
STRONG
EM
SPAN
- allow the user to enter attributes for the
element.
H1
H2
H3
H4
H5
H6
Technique 7.3.2 [priority 1] Verify
that programmatic objects do not create moving content
- Elements:
SCRIPT
- distinguished by (see
discussion)??
OBJECT type =
(@@what are the type attribute values
for Java, etc.?)
EMBED
APPLET
- Moving text may be difficult to read and is inaccessible for many
viewers.
- Allow the user to remove the
SCRIPT
from the document or
create a mechanism to stop the movement.
- @@ what about
OBJECT, EMBED, and APPLET
?
Checkpoint 7.4 - Until user agents
provide the ability to stop the refresh, do not create periodically
auto-refreshing pages
Technique 7.4.A [priority 2] Remove
auto-refresh attributes from META
elements
- Elements:
META �http-equiv="refresh"
�content=
integer_greater_than_zero
- Note:If the "
content
" attribute is a URI this is an
auto-redirect page. Refer to technique 7.5.1
- This page uses auto-refresh which can make the page difficult to read
for some people.
- Allow user option to either:
- Remove the auto-refresh from the document OR
- Create a page with link to new page.
Checkpoint 7.5 - Until user agents provide
the ability to stop auto-redirect, do not use markup to redirect pages
automatically
Technique 7.5.1 [priority 2] Check
auto-redirect attributes on META
elements
- Element:
META http-equiv="refresh"
content="
any-URI
"
.
- This page uses auto-redirect which can make the page difficult to read
for some people.
- Allow the user to remove the auto-redirect from the document and add a
link to the new document.
Guideline 8. Ensure direct accessibility of
embedded user interfaces
Checkpoint 8.1 - Make programmatic
elements such as scripts and applets directly accessible or compatible with
assistive technologies
Technique 8.1.1 [priority
1 if functionality is important and not presented elsewhere, otherwise
Priority 2] Verify that programmatic objects are directly accessible.
- Tools should include means to test the embedded technologies, e.g. java,
at least by running them, preferably by including any test software
supplied for the technology. [Len
Kasday - 23 January 2000]
- Elements:
OBJECT, APPLET
, EMBED or
SCRIPT
.
- This element may not be accessible to all users. Please ensure there is
an accessible interface to this object.
- Ensure that scripts, applets, or other programmatic objects are directly
accessible
- Display a user notification if any of the programmatic elements are in
the document.
Guideline 9. Design for
device-independence
- Checkpoint 9.1 - Provide client-side
image maps instead of server-side image maps except where the regions
cannot be defined with an available geometric shape.
- Checkpoint 9.2 - Ensure that any
element that has its own interface can be operated in a device-independent
manner.
- Checkpoint 9.3 - For scripts,
specify logical event handlers rather than device-dependent event
handlers.
- Checkpoint 9.4 - Create a logical tab
order through links, form controls, and objects.
- Checkpoint 9.5 - Provide keyboard
shortcuts to important links, form controls, and groups of form
controls
Checkpoint 9.1 - Provide client-side image
maps instead of server-side image maps except where the regions cannot be
defined with an available geometric shape
Technique 9.1.1 [priority 1] Check for
use of server-side image maps
Evaluation:
Suggested message:
- Use client-side image maps instead of server-side maps.
Suggested repair:
- Allow the user to convert the server-side image map to a client-side
image map.
Checkpoint 9.2 - Ensure that any element
that has its own interface can be operated in a device-independent manner
Open issues for this technique:
- This technique is strongly tied to Guideline 8 and checkpoint 1.1 (image
maps). Is there redundancy that we can get rid of?
Evaluation:
- Elements:
OBJECT type =
(@@what are the type attribute values
for Java, etc.?)
EMBED
APPLET
Suggested message:
- Ensure this programmatic object can be operated in a device independent
manner.
Suggested repair:
- Display a user notification if any of the programmatic objects are in
the document.
Checkpoint 9.3 - For scripts,
specify logical event handlers rather than device-dependent event
handlers
Technique 9.3.1 [priority 2] Check
scripts for logical event handlers
- Elements: All elements that can contain event handlers
- Requirement: Elements must have a device independent event handler if
they have any of the following device dependent event handlers:
onMouseDown()
onMouseUp()
onClick()
onMouseOver()
onMouseOut()
onMouseMove()
- For scripts, specify logical event handlers rather than device-dependent
event handlers.
Allow the user to add or replace the event handlers according to the
following list:
- "
onMouseDown
" add or replace with
"onKeyDown
"
- "
onMouseUp
" add or replace with "onKeyUp
"
- "
onClick
" add or replace with
"onKeyPress
"
- "
onMouseOver
" add or replace with
"onFocus
"
- "
onMouseOut
" add or replace with "onBlur
"
- "
onMouseMove
" remove or replace with ??@@
Checkpoint 9.4 - Create a logical tab order
through links, form controls, and objects
Open issues for this technique:
- If the tab order jumps around too much it could be confusing to someone
using magnification or a cognitive disability. Can we check for this?
- Elements:
A
AREA
BUTTON
INPUT
OBJECT
SELECT
TEXTAREA
- Requirements:
- May contain a valid "
tabindex
" attribute.
Valid "tabindex
" attribute:
- Must be an integer greater than or equal to zero.
- These controls are missing a tab order. A tab order makes controls
easier to navigate for many users.
- Display the controls and allow the user to set the tabindex of
each.
Checkpoint 9.5 - Provide keyboard
shortcuts to important links, form controls, and groups of form controls
- Elements:
A
AREA
BUTTON
INPUT
LABEL
LEGEND
TEXTAREA
- Requirements:
- If any of these elements are present, at least one of them should
have a valid "
accesskey
" attribute
- There are no keyboard shortcut keys to any of the controls in this
document. Important links and controls should have shortcut keys.
Suggested repair:
- Display the objects that can contain shortcut keys and allow the user to
assign shortcut keys to them.
- Checkpoint 10.1 - Until user agents allow
users to turn off spawned windows, do not cause pop-ups or other windows
to appear and do not change the current window without informing the
user
- Checkpoint 10.2 - Until user agents
support explicit associations between labels and form controls, for all
form controls with implicitly associated labels, ensure that the label is
properly positioned
- Checkpoint 10.3 - Until user agents
(including assistive technologies) render side-by-side text correctly,
provide a linear text alternative (on the current page or some other) for
all tables that lay out text in parallel, word-wrapped columns
- Checkpoint 10.4 - Until user agents handle
empty controls correctly, include default, place-holding characters in
edit boxes and text areas
- Checkpoint 10.5 - Until user agents
(including assistive technologies) render adjacent links distinctly,
include non-link, printable characters (surrounded by spaces) between
adjacent links
Checkpoint 10.1 - Until user agents allow
users to turn off spawned windows, do not cause pop-ups or other windows to
appear and do not change the current window without informing the user
Technique 10.1.1 [priority 1] Check
A
and AREA
elements for valid "target
"
attributes
- How do we handle the "until user agents" clause?
- Is it enough for the document to inform the user that the link will open
in a new window or must we completely avoid new windows?
- Elements:
- Requirements:
- Should not have "
target
" attributes of
"_blank
" or "_new
".
- This anchor element [anchor text] will open a new window that can
disorient some users.
- Allow the user to
- remove the "
target
" attribute or
- use an existing window as the target
Open issues for this technique:
- Do all
APPLET
elements trigger this technique?
- Are there other embedded elements or scripting languages that ought to
trigger this technique?
- Elements:
- Requirement:
SCRIPT
must not contain code of
window.open()
- This script will open a new window that can be disorienting for some
users.
- Allow the user to remove the scripting code that opens a new
window.
Checkpoint 10.2 - Until user agents
support explicit associations between labels and form controls, for all form
controls with implicitly associated labels, ensure that the label is properly
positioned
Refer also to checkpoint 12.4
- Elements:
- Requirement: Text labels must be positioned as the first text
immediately before or after the form control.
- Labels for form controls should be positioned close to their
corresponding form controls. This control [control type] does not have a
closely positioned label.
- Allow the user to reposition labels associated with form controls as
follows:
- Labels for radio buttons and checkboxes should appear after the
radio button or checkbox. For example: [checkbox] oranges, [checkbox]
apples.
- Labels for text fields appear before the text field. For example:
last name [text area].
- Labels for groups of any form control should appear before the
group. For example: choose a city [radio button] Boston [radio button]
Madison.
Checkpoint 10.3 - Until user agents (including
assistive technologies) render side-by-side text correctly, provide a linear
text alternative (on the current page or some other) for all tables that lay
out text in parallel, word-wrapped columns
- Element:
TABLE
- Requirement: A linear version of the table is provided
- Please consult the definition of linearized table. This checkpoint
benefits people with user agents (such as some screen readers) that are
unable to handle blocks of text presented side-by-side; the checkpoint
should not discourage content developers from using tables to represent
tabular information.
- If it has been determined that the table is used for layout (see
Technique 5.1.1) then create a linear version of the table by: [@@insert
heuristics from table linearizer - basically replace
TABLE
markup with text structural markup]. The author will then need to check
that it is readable.
- If it has been determined that the table is used for data (see Technique
5.1.1) then create a linear version of the table by: [@@table linearizer
heuristics? basically, for each cell repeat the column and row headers
associated with it]. The author will then need to check that it is
readable.
- Table linearizer(@@link)
- Trace "HelpDB" (@@link)
- other examples?
Checkpoint 10.4 - Until user agents handle
empty controls correctly, include default, place-holding characters in edit
boxes and text areas
- Elements:
INPUT type="text | checkbox | radio"
TEXTAREA
OPTION
- Requirements
INPUT
elements that have a type of "text",
"checkbox" or "radio"
must have at least one word of text in
their "value
" attribute.
- Between the
TEXTAREA
start and TEXTAREA
end elements must be at least one word of text.
- One
OPTION
in each group contained by
SELECT
elements must have a "selected
"
attribute.
INPUT
element missing value: This form control is missing
placeholder text.
TEXTAREA
missing text: This TEXTAREA
is
missing placeholder text.
OPTION
not selected: At least one OPTION
must
be selected within this group.
INPUT
element missing value: Allow user to enter
placeholder text.
TEXTAREA
missing text: Allow user to enter text.
OPTION
not selected: Display all options and allow user to
select one as "selected".
Checkpoint 10.5 - Until user agents (including
assistive technologies) render adjacent links distinctly, include non-link,
printable characters (surrounded by spaces) between adjacent links
- Element:
A
end element.
- Requirement:
A
sections within the same line of text must
be separated by a sequence of "whitespace, non-whitespace,
whitespace".
- Whitespace is a space, tab, CR, or
- Non-whitespace is any text character.
- These sequential links do not have separating characters: [sequential
links].
- Allow user to insert " | " characters between sequential links. Allow
user to choose another character other than "|" for separator.
Guideline 11. Use W3C technologies and
guidelines
- Checkpoint 11.1 - Use W3C technologies
when they are available and appropriate for a task and use the latest
versions when supported
- Checkpoint 11.2 - Avoid deprecated
features of W3C technologies
- Checkpoint 11.3 - Provide information
so that users may receive documents according to their preferences
- Checkpoint 11.4 - If, after best efforts, you
cannot create an accessible page, provide a link to an alternative page
that uses W3C technologies, is accessible, has equivalent information (or
functionality), and is updated as often as the inaccessible (original)
page
Checkpoint 11.1 - Use W3C technologies when
they are available and appropriate for a task and use the latest versions when
supported
Open issues for this technique:
- Many of these W3C formats are not widely supported yet. Therefore, how
do we deal with this in the meantime? Present the info and let the author
decide?
- Element: ?@@
- Requirements:
- Check for uses of non-W3C technologies such as: PDF, Flash, GIF
images, JPG images, proprietary HTML elements (@@other major
ones??).
- @@link See 1.1.1 for images used for mathematical equations.
- Note. I left out JavaScript because there is not a W3C equivalent
technology yet.
- Non-W3C technology used: W3C technologies have been reviewed for
accessibility issues throughout the design phase and have accessibility
built-in. Many non-W3C formats require specific applications (often called
plug-ins) that are inaccessible or do not work well with assistive
technologies. Using W3C technologies will tend to make pages more
accessible to more people using a wider variety of hardware and software.
If inaccessible technologies (proprietary or not) must be used, equivalent
accessible pages must be provided.
- Suggest that where appropriate, the author:
- convert quicktime movies (others?) into SMIL presentations.
- convert GIF and JPG images with text to text with style sheets.
- convert Flash animations to a combination of valid HTML, SMIL, and
PNG or SVG.
- convert images of math equations to MathML.
- Use a text-only page generator (such as Adobe's PDFtoText) to create an
equivalent accessible page.
Checkpoint 11.2 - Avoid deprecated features
of W3C technologies
- This HTML element [deprecated element] is now deprecated and should not
be used. Use this element instead: [replacement element].
- Allow the user to replace
FONT
with CSS
.
- Allow the user to replace
IMG
and APPLET
with
OBJECT
.
Checkpoint 11.3 - Provide information so
that users may receive documents according to their preferences
- Element: ?@@
- Requirement: ?@@
- Prompt user to specify language of document in technique 4.3.1.
- Use CC/PP or XML/XSLT or other transformations on the server or gateway
to configure a page for various user preferences and device profiles.
- Serve style sheets based on user preferences - use the media types.
- Work with your server system administrator to provide content
negotiation.
- Use browser sniffing on the client to request documents on the
server.
- Use cookies to remember user preferences between sessions and server
documents per those preferences.
- Link to other versions of the document (other formats and
languages).
- If not possible to use content negotiation, indicate content type or
language through markup (e.g., in HTML use "
type
" and
"hreflang
").
Checkpoint 11.4 - If, after best efforts, you
cannot create an accessible page, provide a link to an alternative page that
uses W3C technologies, is accessible, has equivalent information (or
functionality), and is updated as often as the inaccessible (original)
page
- Elements: All elements specified in this document.
- Requirements: Check the document for compliance to the WCAG guidelines
according to the level specified by the user.
- This document does not conform to the WCAG guidelines. If you are unable
to make the necessary repairs to this document then please create another
equivalent page that is accessible and link to it from this document.
- Allow user to insert a link in the document to another more accessible
page.
- Dynamically generated alternative pages [references@@].
- Tools to generate alternative pages [references@@].
Guideline 12. Provide context and
orientation information
- Checkpoint 12.1 - Title each frame to
facilitate frame identification and navigation
- Checkpoint 12.2 - Describe the purpose of
frames and how frames relate to each other if it is not obvious by frame
titles alone
- Checkpoint 12.3 - Divide large blocks
of information into more manageable groups where natural and
appropriate
- Checkpoint 12.4 - Associate labels
explicitly with their controls
Checkpoint 12.1 - Title each frame to facilitate
frame identification and navigation
Technique 12.1.1 [priority 1] Check
FRAME
elements for valid "title
" attributes
- Element:
FRAME
- Requirement: Must have valid "
title
" attribute .
Valid "title
" attribute:
- Missing title for this frame: [frame file name].
- Display the frame content and allow user to enter a new title for the
frame.
Checkpoint 12.2 - Describe the purpose of
frames and how frames relate to each other if it is not obvious by frame
titles alone
@@ covered by 1.1.8?
@@Suggest that if the FRAME "title"
does not describe the
frame that a "longdesc
" is needed?
Checkpoint 12.3 - Divide large blocks of
information into more manageable groups where natural and appropriate
@@Any suggestions??
Checkpoint 12.4 - Associate labels
explicitly with their controls
- Elements:
INPUT
and LABEL
- Requirements:
INPUT
elements must have a valid "id
"
attribute.
LABEL
elements must have a valid "for
"
attribute that matches the ID of one of the INPUT
elements in the document.
- This form control is not explicitly labeled: [form control].
- This label is not explicitly associated with a form control:
[label].
- Allow the user to set the "
id
" attribute for each
INPUT
element in the document.
- Allow the user to set the "
for
" attribute of each
LABEL
element so it matches an INPUT
element.
Guideline 13. Provide clear navigation
mechanisms
- Checkpoint 13.1 - Clearly identify the
target of each link
- Checkpoint 13.2 - Provide metadata to add
semantic information to pages and sites
- Checkpoint 13.3 - Provide information
about the general layout of a site
- Checkpoint 13.4 - Use navigation
mechanisms in a consistent manner
- Checkpoint 13.5 - Provide navigation bars to
highlight and give access to the navigation mechanism
- Checkpoint 13.6 - Group related links,
identify the group (for user agents), and, until user agents do so,
provide a way to bypass the group
- Checkpoint 13.7 - If search functions are
provided, enable different types of searches for different skill levels
and preferences
- Checkpoint 13.8 - Place distinguishing
information at the beginning of headings, paragraphs, lists, etc
- Checkpoint 13.9 - Provide information
about document collections
- Checkpoint 13.10 - Provide a means to
skip over multi-line ASCII art
Checkpoint 13.1 - Clearly identify the
target of each link
- Element:
A
- Requirements:
- Names must be unique for each target.
- Must be meaningful
- Should be terse
Suspicious anchor names:
- click here
- more
- follow this
- greater than 60 characters
- If non-meaningful text found: This link text may not be meaningful when
read on its own: [link text].
- If lengthy text found: This link text is quite long and should be
shortened: [link text].
- Allow user to change the link text and surrounding text.
- Retrieve the
TITLE
of the target page and suggest that as
link text.
- If the author is trying to make a Level Triple A site, Ask the author to
provide supplemental information about the link in the
"
title
" attribute.
Harper, S., Stevens, R., and Goble, C. (1999). Towel: Real World Mobility
on the Web. In Vanderdonckt, J. and Puerta, A., eds.: Computer-Aided Design of
User Interfaces II. Dordrecht, Netherlands: Kluwer Academic Publishers.
Checkpoint 13.2 - Provide metadata to add
semantic information to pages and sites
- Elements:
- Requirements: Must have at least one of these elements in the
document.
- This document does not contain any META information.
- If no
META, ADDRESS, TITLE
or LINK
elements
are found, request information from the author to be stored as meta
information. Examples of content to prompt for:
- title of the page (required for frames, see checkpoint 12.1),
- type of content,
- descriptions of the content of the page,
- conformance claims,
- author information,
- next page in a series (e.g.,
LINK rel="next"
).
- If a
LINK
element is found, check if it is used for style
sheets. If it is, then proceed as if no LINK
element were
found.
- If a
META
element is found, check if it is used to create a
redirect. If it is, then proceed as if no META
element were
found (refer also to checkpoints 7.4 and 7.5).
@@Similar to 13.2.1, yet might be best in own technique??
Checkpoint 13.3 - Provide information about
the general layout of a site
@@Machine checkable? Generate user notification?
Checkpoint 13.4 - Use navigation
mechanisms in a consistent manner
@@Machine checkable? Generate user notification?
Checkpoint 13.5 - Provide navigation bars to
highlight and give access to the navigation mechanism
@@Machine checkable? Generate user notification?
Checkpoint 13.6 - Group related links, identify
the group (for user agents), and, until user agents do so, provide a way to
bypass the group
Open issues for this technique:
- WCAG question: can we suggest that links be grouped by
DIV or
SPAN
?
- WCAG question: is the use of
MAP
to group links completely
agreed upon?
This suggests another technique that is not widely supported by user
agents.
- Element: Several
A
elements all in one row or column of
table and/or separated only by
BR
elements,
- or a few characters such as "] [" or " | " or
- Requirement: links should be grouped by
SPAN,DIV
or
MAP
elements.
- Groups of links should be grouped with a structural element.
- Ask the user if an identified list of links should be grouped.
- If the user wants to group the links, use one of the following
techniques
- a
MAP
element
SPAN
or DIV
with appropriate
"title
"
- Suggest that the user provide a link to bypass the group or that they
move the group to the bottom of the page or that they use a high
"
tabindex
" attribute value.
Checkpoint 13.7 - If search functions are provided,
enable different types of searches for different skill levels and
preferences
- Element:
FORM
- Requirement: Check if a
FORM
is used to submit a
search.
- When providing search functionality, content developers should offer
search mechanisms that satisfy varying skill levels and preferences. Most
search facilities require the user to enter keywords for search terms.
Users with spelling disabilities and users unfamiliar with the language of
your site will have a difficult time finding what they need if the search
requires perfect spelling. Search engines might include a spell checker,
offer "best guess" alternatives, query-by-example searches, similarity
searches, etc.
Checkpoint 13.8 - Place distinguishing
information at the beginning of headings, paragraphs, lists, etc
@@Machine checkable? Generate user notification?
Checkpoint 13.9 - Provide information about
document collections
- Is there a way to use RDF to describe document collections?
- Elements: @@?
LINK, A
- Requirement: If the page is part of a collection, such as a slide show,
or a chapter in a book, the previous and next pages ought to be marked as
such.
- Bundled documents can facilitate reading off-line.
- In HTML/XHTML specify document collections with the
LINK
element and the "rel
" and "rev
" attributes.
- Suggest that that the author create a collection by building an archive
(e.g., with zip, tar and gzip, stuffit, etc.) of the multiple pages.
Checkpoint 13.10 - Provide a means to skip
over multi-line ASCII art
- See 1.1.13 for algorithm to find ASCII art
- Elements:
PRE
and XMP
- Requirements: A link must be provided to skip over ASCII art.
- A link must be provided to skip over this character based (ASCII art)
artwork: [display artwork]
- Allow user to insert a link in the document that skips over the ASCII
art.
- Set title of link to "Skip Over ASCII Art" so it can be detected in
future.
Guideline 14. Ensure that documents
are clear and simple
- Checkpoint 14.1 - Use the clearest and
simplest language appropriate for a site's content
- Checkpoint 14.2 - Supplement text with graphic or
auditory presentations where they will facilitate comprehension of the
page
- Checkpoint 14.3 - Create a style of
presentation that is consistent across pages
Checkpoint 14.1 - Use the clearest and
simplest language appropriate for a site's content
@@Check document using fog index? Generate user notification?
Checkpoint 14.2 - Supplement text with graphic or
auditory presentations where they will facilitate comprehension of the
page
@@Machine checkable? Generate user notification?
Checkpoint 14.3 - Create a style of presentation
that is consistent across pages
- @@This requires looking at pages throughout the site. Need two levels of
checking: page vs site?
- Elements:
STYLE
and LINK
- Requirements:
- The properties of
STYLE
elements should be consistent
between pages.
- The names of external style sheets (referenced with
LINK
elements) should be consistent between pages.
- This should be verified by the author. There are good reasons to use
different styles between pages.
- Consistent page layout and recognizable graphics benefit all users. In
particular, they help people with cognitive disabilities or who have
difficulty reading.
- If style properties vary between pages, or various external style sheets
are used, suggest the author consolidate style properties into external
style sheets and use consistently.
After evaluating a document, an evaluation and/or repair tool should
provide the user with a document rating. The rating is based on conformance to
the W3C Web Content
Accessibility Guidelines and will be:
- Level "A": all Priority 1 checkpoints are
satisfied;
- Level "Double-A": all Priority 1 and 2 checkpoints are
satisfied;
- Level "Triple-A": all Priority 1, 2, and 3 checkpoints
are satisfied;
Some checkpoints can not be checked by a software program and will require
user evaluation. The user must be informed of the items that they must
check.
Refer to the Rating Algorithm
for Evaluation of Web Pages by Len Kasday.
- an image file suffix (see Appendix B)
- the single word "Image", "Photo"
- the word "images" �(e.g. as in "turn on images").
Appendix B - Image File
Suffixes
Appendix C - Placeholder OBJECT
text equivalent
Appendix D - Sound File
Suffixes
- .wav
- .au
- .snd
- .dwd
- .iff
- .svx
- .sam
- .smp
- .vce
- .voc
- .pcm
- .aif
Appendix E - Placeholder
NOSCRIPT
text
- {NOSCRIPT text goes here}
Appendix F - Placeholder
TABLE "summary"
text
- Summary
- Table
- Table Summary
Appendix G - Placeholder table
header "abbr
" text
Appendix H - Placeholder
FRAME "title"
text
Appendix I - Applet Executable
Suffix
Appendix J - Bullet
Identification
An image will be identified as a bullet if it has the following
characteristics:
Identifying Bullets
page
Appendix K - Horizontal Rule
Identification
An image will be identified as a horizontal rule if it has the following
characteristics:
Identifying HRs
page
Appendix L - Links To Associated
Sites
- Bobby - Accessibility evaluator
tool
- Lynx Viewer -
Displays a text-only view of web pages
- A-Prompt - Accessibility
evaluator and repair tool
@@link to WCAG and ATAG glossaries?
- Programmatic object
- An object that is embedded in a document with the SCRIPT or
APPLET
elements, and sometimes with the OBJECT or EMBED
elements. @@need to clarify the definition and then use it.


WriteOnlyColumn¶
-
class
dbbase.column_types.
WriteOnlyColumn
(*args, **kwargs)[source]¶ Bases:
sqlalchemy.sql.schema.Column
This class creates a subclassed column that identifies it as write only.
The use case for it derives from the need to screen out columns such as passwords from user tables.
Methods
all_
()Produce a
_expression.all_()
clause against the parent object.any_
()Produce a
_expression.any_()
clause against the parent object.argument_for
(dialect_name, argument_name, …)Add a new kind of dialect-specific keyword argument for this class.
asc
()Produce a
_expression.asc()
clause against the parent object.between
(cleft, cright[, symmetric])Produce a
_expression.between()
clause against the parent object, given the lower and upper range.bool_op
(opstring[, precedence])Return a custom boolean operator.
cast
(type_)Produce a type cast, i.e.
collate
(collation)Produce a
_expression.collate()
clause against the parent object, given the collation string.compare
(other[, use_proxies, equivalents])Compare this ColumnElement to another.
compile
(default[, bind, dialect])Compile this SQL expression.
concat
(other)Implement the ‘concat’ operator.
contains
(other, **kwargs)Implement the ‘contains’ operator.
copy
(**kw)Create a copy of this
Column
, uninitialized.desc
()Produce a
_expression.desc()
clause against the parent object.distinct
()Produce a
_expression.distinct()
clause against the parent object.endswith
(other, **kwargs)Implement the ‘endswith’ operator.
get_children
([schema_visitor])used to allow SchemaVisitor access
ilike
(other[, escape])Implement the
ilike
operator, e.g.in_
(other)Implement the
in
operator.is_
(other)Implement the
IS
operator.is_distinct_from
(other)Implement the
IS DISTINCT FROM
operator.isnot
(other)Implement the
IS NOT
operator.isnot_distinct_from
(other)Implement the
IS NOT DISTINCT FROM
operator.label
(name)Produce a column label, i.e.
like
(other[, escape])Implement the
like
operator.match
(other, **kwargs)Implements a database-specific ‘match’ operator.
notilike
(other[, escape])implement the
NOT ILIKE
operator.notin_
(other)implement the
NOT IN
operator.notlike
(other[, escape])implement the
NOT LIKE
operator.Produce a
_expression.nullsfirst()
clause against the parent object.Produce a
_expression.nullslast()
clause against the parent object.op
(opstring[, precedence, is_comparison, …])Produce a generic operator function.
operate
(op, *other, **kwargs)Operate on an argument.
params
(*optionaldict, **kwargs)references
(column)Return True if this Column references the given column via foreign key.
reverse_operate
(op, other, **kwargs)Reverse operate on an argument.
self_group
([against])Apply a ‘grouping’ to this
_expression.ClauseElement
.shares_lineage
(othercolumn)Return True if the given
_expression.ColumnElement
has a common ancestor to this_expression.ColumnElement
.startswith
(other, **kwargs)Implement the
startswith
operator.unique_params
(*optionaldict, **kwargs)Attributes
anon_label
Provides a constant ‘anonymous label’ for this ColumnElement.
base_columns
bind
comparator
default
description
dialect_kwargs
A collection of keyword arguments specified as dialect-specific options to this construct.
dialect_options
A collection of keyword arguments specified as dialect-specific options to this construct.
dispatch
expression
Return a column expression.
foreign_keys
info
is_clause_element
is_selectable
key
kwargs
A synonym for
DialectKWArgs.dialect_kwargs
.onupdate
primary_key
proxy_set
quote
Return the value of the
quote
flag passed to this schema object, for those schema items which have aname
field.server_default
server_onupdate
supports_execution
table
timetuple
type


2017
Drakkar/MyOcean Workshop registration
Registration
for Workshop are closed
http://doodle.com/poll/qgtnvcxas8cvfkgi
Workshop
Registration fees:
There
will be a registration fee
of 30€/day
to contribute to the workshop organization.
The
fee should be paid in cash (or bank check from French banks, no credit
card) on site.
A receipt
will be provided.
3
days: 80 €
2 days: 60 €
1 day : 30€
Evening
diner Monday 16 January
You can also register for the Monday 16 January evening diner at Café
NoName.
A
contribution of 20€ will be asked to each participant
to
be
paid
on site in Cash, Credit Card (or Checks from French Banks).
Choice
of menu will sent early January.
Snoe
show
Hike on Sunday 15 January
You
can already register for the snow-shoe hike on Sunday 24 if you
intend to come.
Confirmation of your registration (through a
dedicated Doodle) will be asked early January
for the final organisation of the hike. A small contribution will
be asked for the pic-nic and
the rental of the snow-shoes.


So I've build a simple measurement unit using this guide: http://openenergymonitor.org/emon/buildingblocks/how-to-build-an-arduino-energy-monitor-measuring-current-only
It works fine on larger loads but fails to measure currents lower than 0.3 to 0.27 Amps.
Is there anything I could do about that? Changing the calibration value would mean less accuracy in higher ranges.
Re: Problems with low currents
Changing the calibration won't help you. Read "Measurement implications of ADC resolution at low current values" in Building Blocks.
What is the maximum current you want to measure, and what CT are you using? You might be able to improve the voltage seen by the ADC by changing the value of the burden resistor.
Re: Problems with low currents
I'm using the sct-013-000. Since my appliance leakage current interrupter is only built for 40 Amps I need to measure from 0-40 Amps. I'm using a 3.3volt Arduino clone and a burden of 33ohms with a calibration value of about 55.
What would you suggest?
Re: Problems with low currents
For a 3.3 V Arduino, you need a rms voltage across the burden resistor of about 1.1 V. The CT produces 50 mA per 100 A, therefore 20 mA at your maximum current of 40 A. So you need a burden resistor that develops 1.1 V @ 20 mA. 56 Ω will probably be OK. (It just eats a little way into the allowance for component tolerances, but use 51 Ω if you're happier.) That should lower the minimum you can measure to around 180 mA. The calibration constant should be 35.71.
Re: Problems with low currents
Okay, so I've set up a new board with a 56 Ω resistor and your calibration value. However I'm confused why the power Usage doesn't rise by 3.8 Amps when I plug in my electric sandwich maker which is rated for 3.8 amps. It only rises by about 2.1 Amps.
I'm measuring inside my breaker box on the N (blue) wire. Most likely I'll have to replace that with 3 CTs (one for each phase), right?
Re: Problems with low currents
This is the first time you mentioned a 3-phase supply. I think you need to study the theory of 3-phase: The neutral current is the vector sum, not the arithmetic sum, of the three phase currents. That means that if the currents in the three phases are equal, there should be, and you should measure, zero current in the neutral.
Does your sandwich toaster have a 3-phase supply? I very much doubt it. You say the current "rises" by 2.1 A, but what was it displaying before, and what is consuming that current?
I think it is quite likely that you are measuring noise, either current in adjacent conductors or digital noise from the Arduino itself. What do you measure with your CT in free space a long way from any current-carrying conductor?
Re: Problems with low currents
Well, I'm assuming it is 3-phase since my electric stove is connected to it and there are 4 wires coming out of the wall. Here's a Picture of the breaker box cabling http://i.imgur.com/TBB65MW.jpg
Before, it was displaying about 0.6 - 0.7 Amps which is the idle power usage of my computer/NAS etc. running. I'm sure that isn't noise because when I turn off the computer it does fall for about 0.4. Also, the measured current changes appropriately when I turn on my washing machine, my stove or just a lamp.
Re: Problems with low currents
You do indeed have a 3-phase supply, and you are measuring the neutral (imbalance) current. Therefore, unless all the loads are on the same phase, you cannot simply add and subtract the scalar values of current, because there might be a 120° phase difference between them even if they are well-behaved resistive loads. If there is an induction motor or a switched-mode power supply, the phase angle is anyone's guess and so is the resulting current.
You can only perform a meaningful check on the calibration by measuring the current in the phase conductor (brown, black or grey) or the corresponding neutral conductor of a single resistive load. Measuring the current in the combined neutral conductor is meaningless for this purpose.
Re: Problems with low currents
My 2 other CTs just arrived. By measuring all 3 phases everything works like one would expect. Thanks for your quick and useful support.


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We start each project by understanding your business goals, the user's needs and the product requirements
Then we help translate them into an effective and elegant solutions
Before we sign a contract or write a fine code our team will spend the necessary time needed to understand your product vision.
The outcome of this scoping session is proposal or high-level statement of work.
Based on your requirements, we can provide a complete offering or just the pieces you need.
CONTACT US
DELANI STUDIO
2019


A malignant tumor that has developed from cells in the breast. Usually breast cancer either begins in the cells of the lobules, which are the milk-producing glands, or the ducts, the passages that drain milk from the lobules to the nipple. Less commonly, breast cancer can begin in the stromal tissues, which include the fatty and fibrous connective tissues of the breast


Pinterest has to be my favorite way to procrastinate. It is a website filled with 'do it yourself' projects, clothes, and inspiration. The website is very clean cut with sharp lines and eye pleasing colors. Words to describe this webpage visually would be clean, nonclutered, elegant, light, and colorful. This website is a place for women (or men) to come to, to get inspiration for anything from clothes, to hair, to home decor. It is definitely more of a fun yet practical website, and the visual design matches the purpose of the website extremely well. Not only do I love how much time I can waste on this website, but I love the design, layout, and ease of use.
Fanfiction is a website that budding writers can come and submit pieces of their writing for the world to read. In general, the stories are based off of other published books, movies, or games, but still maintain originality and imagination. I am an avid reader and I go to fanfiction often to explore new authors and read free stories from promising new authors. The website design is extremely simple. It is bare minimum of web design possible. To describe it in words would be basic, simple, and light. The purpose of this website is a community to sumbit and read imaginative pieces of writing. A overdesigned, cluttered website would deter from this purpose. I wouldn't mind if they maybe did a small update though. In the 10 years I've used this site, it hasn't changed at all. Change is sometimes good... just saying ;)
Amazon might not be the most exciting website in the world, but to me it has to be one of the best designed websites ever. If I ever need to buy something with no hassle, I always know that I can go straight to Amazon and I will find what I am looking for. The web design is easy to use, uncluttered, elegant, and colorful. I am always buying ebooks off of Amazon as well as clothes, computer accessories, and beauty products. The website walks you through the purchase process and leaves you at the end feeling happy and successful!


[1]
WORLD COUNTRIES/ SENIOR TRADE OFFICIALS/ AGREEMENT/ COUNTRIES BANGLADESH DHAKA/ CAPITAL/ ASIAN 49 COUNTRIES/ OFFICERS/ TWO


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Defined Type: compliance_markup::map
- Defined in:
- manifests/map.pp
Overview
A wrapper to ensure that the mapper is called during the appropriate phase of the catalog compile.
Defines appear to be run after all classes
The options hash is passed directly to the compliance_map
function
7 8 9 10 11 |
# File 'manifests/map.pp', line 7
define compliance_markup::map (
$options = {}
) {
compliance_map($options)
}
|


Break Time? Grab a healthy Snack!
| Fruits | Blueberries, Raspberries, BlackBerries, Bananas, Apples | Blueberries (4-8oz per serving), Raspberries (2-4oz per serving), Blackberries (2-4oz per serving), Banana (medium-size) |
| Nuts | Almonds | Expensive, but a healthy choice in moderation. Serving Size: 1/4 cup. |
| Cottage Cheese | Brand is irrelevant, just make sure the fat content is moderately low and protein is high. | Serving size: 8oz. Excellent day/night snack. May add blueberries and 1 tbsp honey to enhance flavor. |
| Greek Yogurt | Chobani, FAGE, Muller, Oikos | Serving Size: 1cup. Ensure that that there is less sugar. Tip: you may add 3oz of fruits to your yogurts. |
| Vegetables | Baby Carrots, Cauliflower, Edamame, Avacado, Peppers | A good portion size for these is approx 4-6oz. You may also dip them in hummus. Approx 3oz of hummus. |
| Water | Evian Natural Spring Water, FIJI Natural Artesian Water, Gerolsteiner Mineral Water, Perrier Mineral Water, Mountain Valley Spring Water, | Thats right. Water could be a great meal suppresser and also will keep you more awake and sharp. |
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|


Hi! I'm Anish Krishnan!
AK
I'm a full stack developer and student currently studying at Monta Vista.
I am currently looking for more professional work for web development.
Skills
Skills
Click a skill to see which project it's used in.
Java
Python
Ruby
PHP
MySQL
Parse
C++
Firebase
Android
Node
Rails
Git
Heroku
React
LaTeX
Phonegap
HTML
CSS
JS
JQuery
Angular
AJAX
Gulp.js
Materialize
Hobbies
Hobbies
Click a hobby to learn more.
-
Programming
The difference between having programming as a hobby and as a career is that as a career, I would usually be doing it for somebody else, for the sake of making money. Doing it as a hobby lets me enjoy programming for the sake of programming, lets me pursue my own hobbies, and it's a great way to learn more.
-
Hackathons
Hackathons are a great place to do programming as a hobby, with a little motivation and hope for winning a prize fueling me through the night. More importantly however, I believe hackathons are a great place to meet new people, learn new languages and tools altogether, and practice delivering a polished product while working with a team under high pressure and little time conditions, yet facing no consequences, making it easier to learn from.
-
Photography
I enjoy all the math, science, and logic of my hobbies, but sometimes it's nice to do something different, something artistic. I enjoy photography as it's a great way to capture the world and it's beauty, my favorite type being landscape, scenery, or background shots.
-
Dancing
I enjoy all the math, science, and logic of my hobbies, but sometimes it's nice to do something different, something artistic, and while I only had to take this for the general education requirements, I learned to enjoy it just like I do ice skating and archery, as it's taught me much of the same thing: Simply keep trying, trying hard, and you will be able to do what you want to.
-
Reading
I wish I had more time to read. I love reading, and I dare say I enjoy it more than other forms of entertainment. it's quite enticing to read for me; fictional books require you to have a level of imagination to fully appreciate and enjoy. They're a great medium to learn from and a healthy form of entertainment.
-
Basketball
Most of my hobbies, with the exception of social dancing and archery, are quite lonesome activities. Basketball is a fun hobby for me to enjoy with my friends, when we're all around to enjoy ourselves, and it's a great way to practice working together on a common goal.
-
Archery
I enjoy all the math, science, and logic of my hobbies, but sometimes it's nice to do something different, something artistic, and while I only had to take this for the general education requirements, I learned to enjoy it just like I do ice skating and dancing, as it's taught me much of the same thing: Simply keep trying, trying hard, and you will be able to do what you want to.
-
Ice Skating
I enjoy all the math, science, and logic of my hobbies, but sometimes it's nice to do something different, something artistic, and while I only had to take this for the general education requirements, I learned to enjoy it just like I do dancing and archery, as it's taught me much of the same thing: Simply keep trying, trying hard, and you will be able to do what you want to.
Projects
Developed from scratch a Rails e-commerce site to advertise/sell SAT II Chem classes.
Made with ❤ and:
anish-krishnan.github.io/myoSport
App to record, replay, and learn motion using Myo, Pebble, and Machine Learning.
Made with ❤ and:
anish-krishnan.github.io/MyoMessenger
IM app to let the speech-impaired send translated Sign Language gestures using Myo.
Made with ❤ and:
Crowd-sourced location finder app to pin anything and let others find everything.
Made with ❤ and:
100,000 searchable jobs displayed on a map, filterable by location, skill, & user stats.
Made with ❤ and:
anish-krishnan.github.io/ViewMe
Control any 3D object with any pc/phone camera using gestures with your torso.
Made with ❤ and:
SJSU CS Club portal to publish events, news and important information for viewing.
Made with ❤ and:
Hosted & led my hackathon to teach coding & close the gender/diversity gap in tech.
Made with ❤ and:
anish-krishnan.github.io/Slapp
App for smartwatches/myos/phones to detect slapps & exchange contact + otherinfo.
Made with ❤ and:
anish-krishnan.github.io/MixChat
Universal IM app to talk freely between multiple IMs like FB, gmail, kik, skype, etc.
Made with ❤ and:
Preview a t-shirt on yourself with any pc/phone camera with just an image of the shirt.
Made with ❤ and:
anish-krishnan.github.io/UPITTY
Mobile app using openCV to wake up users that are dozing off when driving/working.
Made with ❤ and:
shantulshi.github.io/CodeRAIcer
Educational app teaching users to write racing AIs used to compete with other users.
Made with ❤ and:
sleepy-sands-6336.herokuapp.com
Location based image sharing app that lets users post & view images anonymously.
Made with ❤ and:
github.com/anish-krishnan/FunFacts
A simple android app that gets a random fact from multiple online sources.
Made with ❤ and:
github.com/anish-krishnan/SlideStoryBeginnings
A simple android app that's a prototype of a new way to enjoy stories and media.
Made with ❤ and:
github.com/anish-krishnan/GolfTrakr
A simple android app that's allows users to keep track of their golf score per hole.
Made with ❤ and:
github.com/anish-krishnan/Stormy
A simple android weather app made with OkHTTP, Forecast.io, and SQLite.
Made with ❤ and:
github.com/anish-krishnan/TreeBlog
A simple android app that displays all the Treehouse Blog Posts in an easily navigable fashion.
Made with ❤ and:
Contact
I am currently looking for developer work, and I am available for internships and other work over the summer. If you have any questions or offers, please don't hesitate to contact me!
Please use any medium to contact me; email works best.
Otherwise, calling or facebook message is good too.


Australia gives $300 million loan to Papua New Guinea
by ReutersMELBOURNE (Reuters) - Australia on Saturday said it would provide a loan of $300 million as direct budget assistance for the Pacific island of Papua New Guinea and aid its economic reforms and government financing.
Australia's ties with PNG and other small, developing countries in the Pacific have gained significance as China expands its influence in a region dominated by the United States and its allies since World War Two.
Though rich in natural gas, crude oil, gold and copper, among other commodities, PNG has seen its revenues hit in recent years by a downturn in global commodity prices, and has increasingly turned to China for financing.
"This assistance reflects the Australian national interest in a stable and prosperous Papua New Guinea," Alex Hawke, Australia's minister for international development and the Pacific, said in a statement.
"It builds on our two countries' strong economic partnership, which includes support for economic reform," he said.
"It will also benefit Papua New Guinean and Australian businesses by increasing the availability of foreign exchange in the country and by supporting trade and investment."
In August, PNG said it was seeking to refinance its entire government debt, turning to Beijing for help.