Please refer to the errata for this document, which may include some normative corrections.
See also translations.
Copyright © 2008 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark and document use rules apply.
This document defines the tests that provide the basis for making a claim of W3C® mobileOK™ Basic conformance and are based on W3C Mobile Web Best Practices [Best Practices]. The details of how to claim mobileOK conformance will be described separately. Providers of content which passes the tests have taken some steps to provide a functional user experience for users of basic mobile devices whose capabilities at least match those of the Default Delivery Context (DDC).
mobileOK Basic primarily assesses basic usability, efficiency and interoperability. It does not address the important goal of assessing whether users of more advanced devices enjoy a richer user experience than is possible using the DDC.
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
This document was developed by the Mobile Web Best Practices Working Group as part of the Mobile Web Initiative.
Please see the Working Group's implementation report. A complete list of the editorial changes since the previous version of this document is available.
Please send comments about this document to public-bpwg-comments@w3.org (with public archive).
This document defines machine-verifiable tests, based on the W3C Mobile Web Best Practices [Best Practices]. Although content authors are not expected to use this document directly, participants of the Working Group expect tools that implement the tests defined in this document to greatly improve the authoring of content that addresses the browsing experience of users on a broad range of devices.
This document has been reviewed by W3C Members, by software developers, and by other W3C groups and interested parties, and is endorsed by the Director as a W3C Recommendation. It is a stable document and may be used as reference material or cited from another document. W3C's role in making the Recommendation is to draw attention to the specification and to promote its widespread deployment. This enhances the functionality and interoperability of the Web.
This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.
1 Introduction
1.1 Scope
1.1.1 Relationship to Best Practices
1.1.2 Out of Scope
1.1.3 Beyond mobileOK
1.2 Applicability
1.3 Claiming mobileOK conformance
2 Conformance
2.1 Use of Terms must, should etc.
2.2 Validity of the Tests
2.3 Testing Outcomes
2.4 Conduct of Tests
2.4.1 Order of Tests
2.4.2 HTTPS
2.4.3 HTTP Request
2.4.4 HTTP Response
2.4.5 Meta http-equiv Elements
2.4.6 CSS Style
2.4.7 Included Resources
2.4.8 Linked Resources
2.4.9 Validity
2.4.10 White Space
3 mobileOK Basic Tests
3.1
AUTO_REFRESH and REDIRECTION
3.2
CACHING
3.3
CHARACTER_ENCODING_SUPPORT
and CHARACTER_ENCODING_USE
3.4
CONTENT_FORMAT_SUPPORT and
VALID_MARKUP
3.5
DEFAULT_INPUT_MODE
3.6
EXTERNAL_RESOURCES
3.7
GRAPHICS_FOR_SPACING
3.8
IMAGE_MAPS
3.9
IMAGES_RESIZING and IMAGES_SPECIFY_SIZE
3.10
LINK_TARGET_FORMAT
3.11
MEASURES
3.12
MINIMIZE
3.13
NO_FRAMES
3.14
NON-TEXT_ALTERNATIVES
3.15
OBJECTS_OR_SCRIPT
3.15.1 Object Element Processing Rule
3.16
PAGE_SIZE_LIMIT
3.17
PAGE_TITLE
3.18
POP_UPS
3.19
PROVIDE_DEFAULTS
3.20
STYLE_SHEETS_SUPPORT
3.21
STYLE_SHEETS_USE
3.22
TABLES_ALTERNATIVES
3.23
TABLES_LAYOUT
3.24
TABLES_NESTED
A Acknowledgments (Non-Normative)
B References (Non-Normative)
C Relationship between Best Practices and mobileOK Tests (Non-Normative)
mobileOK Basic is a scheme for assessing whether Web resources (Web content) can be delivered in a manner that is conformant with Mobile Web Best Practices [Best Practices] to a simple and largely hypothetical mobile user agent, the Default Delivery Context.
This document describes W3C mobileOK Basic tests for delivered content, and describes how to emulate the DDC when requesting that content.
The intention of mobileOK is to help catalyze development of Web content that provides a functional user experience in a mobile context. It is not a test for browsers, user agents or mobile devices, and is not intended to imply anything about the way these should behave.
mobileOK does not imply endorsement or suitability of content. For example, it must not be assumed that a claim that a resource is mobileOK conformant implies that it is of higher informational value, is more reliable, more trustworthy or is more appropriate for children than any other resource.
mobileOK Basic tests are based on a limited subset of the Mobile Web Best Practices. Their outcome is machine-verifiable, hence claims of mobileOK Basic conformance are easy to check.
Content passing the tests demonstrates that the content provider has taken basic steps to provide a functional experience for mobile users.
mobileOK Basic conformance should be considered only a first step towards building a harmonized experience for mobile users. Conformance merely demonstrates that a basic experience is available, interoperable with a large number of mobile devices. mobileOK Basic conformance says nothing about richer, more sophisticated, experiences that may be available, nor does it say anything about whether other guidelines for development of Web content (such as [WCAG 1.0]) have been followed.
Some Best Practices, like TESTING, are advisable but do not meaningfully translate into concrete tests.
The tests assess whether the content can be provided in a way that achieves basic usability, efficiency, and interoperability with mobile devices. The tests should not be understood to assess thoroughly whether the content has been well-designed for mobile devices.
The Best Practices, and hence the tests, are not promoted as guidance for achieving the optimal user experience. The capabilities of many devices exceed those defined by the DDC. It will often be possible, and generally desirable, to provide an experience designed to take advantage of the extra capabilities.
Content providers should provide an experience that is mobileOK Basic conformant to ensure a basic level of interoperability. Providers are encouraged to provide enhanced experiences as well when these are appropriate to their application and devices that are accessing them.
The tests apply to a URI. Passing the tests means that when accessed as described in 2.4.3 HTTP Request, resolving a URI will result in mobileOK Basic conformant content that is delivered in a mobileOK Basic conformant manner.
That is, the tests do not apply solely to content or document instances. Many Best Practices relate not just to the document (e.g. VALID_MARKUP), but to how it is delivered to a mobile device (e.g. CACHING).
mobileOK Basic says nothing about what may be delivered to non-mobile devices.
A standard mechanism will be defined that allows content providers to claim that a URI or group of URIs, such as a Web site, conforms to mobileOK Basic. It will be possible to make claims in a machine-processable form. It will also be possible to notify end users of the presence of the claim by means of a human-readable mark.
The details of the mechanism for claiming mobileOK conformance will be described separately.
Where terms are used with the meanings defined in [RFC 2119] they are highlighted in the text e.g. must.
mobileOK tests are only meaningful when the URI under test resolves to HTML content delivered over HTTP.
Individual tests may result in PASS or FAIL. PASS is required from all tests in order to claim mobileOK Basic conformance. In any test, PASS is achieved if and only if there are no FAILs. No specific PASS outcome is defined for any test.
Tests may also generate a number of informative warnings which do not affect whether a test has PASSed or not. A warning may indicate that it could not be conclusively determined whether the content under test conforms to a Best Practice (and thus does not FAIL), or may indicate that the content under test is close to violating a Best Practice.
mobileOK Basic does not prescribe the order in which tests are to be carried out as they may be executed independently. Some tests have been designed to assess aspects of the content that are disallowed by other tests; this is deliberate and is intended to allow testing environments to provide as much information as possible.
For example the test for 3.21
STYLE_SHEETS_USE
points out that
style sheets should be used in preference to markup elements such as
center
, even though the center
element is also
disallowed by the test for 3.4
CONTENT_FORMAT_SUPPORT and
VALID_MARKUP.
Creators of implementations of the tests described in this document are encouraged to provide as much information as possible to users of their implementations. Where possible they should not stop on FAIL and specifically they should:
Provide information about the cause of warning or failure (each warn and FAIL is individually identified);
Continue individual tests as far as is possible;
Carry out as many tests as is reasonable.
Note:
Arbitrary root certificates (including self-signed certificates) should be regarded as trusted.
When resolving a URI, if the URI has the scheme https
:
If the certificate presented does not match the requested URI, FAIL
If the certificate has expired, or is not yet valid, warn
If certificate validation otherwise fails, FAIL
The following HTTP request headers inform the server that it should deliver content that is compatible with the Default Delivery Context.
Use the HTTP GET
method when making requests, except for
3.10
LINK_TARGET_FORMAT
where the HEAD
method may be used (See 2.4.8 Linked Resources for a
discussion of the POST
method).
Include a User-Agent
header which starts exactly as follows (indicating the Default Delivery Context, and which may be extended in accordance with [RFC 2616] Section 14.43, User-Agent Header) :
User-Agent: W3C-mobileOK/DDC-1.0 (see http://www.w3.org/2006/07/mobileok-ddc)
Include an Accept
header indicating that Internet media
types understood by the Default Delivery Context are accepted by
sending exactly this header:
Accept: application/xhtml+xml,text/html;q=0.1,application/vnd.wap.xhtml+xml;q=0.1,text/css,image/jpeg,image/gif
Include an Accept-Charset
header indicating that only
UTF-8 is accepted by sending exactly this header:
Accept-Charset: UTF-8
Do not include cookie related headers.
Include authentication information if required (see 2.4.4 HTTP Response). Once authentication information has been included in a request, subsequent requests for the same realm must include authentication information as described in Section 2 and under "domain" in Section 3.2.1 of [RFC 2617].
Implementations must support URIs with both
http
and https
scheme components.
Note:
As noted under 2.4.7 Included Resources and 2.4.8 Linked Resources the URIs that are relevant to
mobileOK are those that, when represented in an absolute form,
have either the http
or the https
scheme. Requests should not be made for URIs
with schemes other than http
and
https
.
Note:
Implementations must support basic and digest authentication.
Note:
Below, note that a 404 or 5xx response for the resource under test does not result in a FAIL in order to allow for the possibility of testing an application's error page.
Note:
If the test below results in a FAIL, do not proceed with further tests. Otherwise, the mobileOK Basic Tests should be applied to the content.
If an HTTP request does not result in a valid HTTP response (because of network-level error, DNS resolution error, or non-HTTP response), FAIL
If the HTTP status indicates redirection (status code 3xx):
Do not carry out tests on the response
If the response relates to a request for the resource under test, or any of its Included Resources (see 2.4.7 Included Resources):
Include the size of the response in the "total size" as described under 3.16 PAGE_SIZE_LIMIT
Include this response under the count as described under 3.6 EXTERNAL_RESOURCES
If there is no HTTP Location
header, FAIL.
If the URI identified by the HTTP
Location
header is a relative URI, create an absolute URI
by combining the value of the Location
header with the
absolute URI of the request to which this is a response, warn
If the resulting URI is not a URI with the scheme
http
or https
, FAIL.
Re-request the resource using the URI formulated above.
If the HTTP status indicates that authentication is required (e.g. status code 401):
If the response relates to a request for the resource under test, or any of its Included Resources (see 2.4.7 Included Resources):
If authentication information was supplied in the HTTP request (i.e. authentication failed) or if no authentication information is available, FAIL
Carry out tests on the response
Include the size of the response in the "total size" as described under 3.16 PAGE_SIZE_LIMIT
Include this response under the count as described under 3.6 EXTERNAL_RESOURCES
Re-request the resource using authentication information
If the response relates to a request for a linked resource (see 2.4.8 Linked Resources):
Continue with the test (see 3.10 LINK_TARGET_FORMAT , i.e. do not re-request the resource with authentication information), warn
If the HTTP status code is 404 or 5xx
If the response relates to a request for the resource under test, continue with tests on the response and warn
If the response relates to a request for a linked resource (see 2.4.8 Linked Resources), continue with the test (see 3.10 LINK_TARGET_FORMAT ) and warn
Otherwise (i.e. for Included Resources), FAIL
If the HTTP status represents failure (4xx), other than 404, a request for authentication (e.g. 401) or a 406 when carrying out the 3.15.1 Object Element Processing Rule, FAIL
Documents can include meta
elements with an
http-equiv
attribute; these are sometimes considered
substitutes for HTTP response headers.
mobileOK Basic test implementations must ignore values specified in such elements, aside from the following:
The Refresh
header as specified in 3.1
AUTO_REFRESH and REDIRECTION
The Content-Type
header as specified in 3.3
CHARACTER_ENCODING_SUPPORT
and CHARACTER_ENCODING_USE
The Cache-Control
header as specified in 3.2
CACHING
Check for consistency with HTTP headers, as follows:
For each meta
element with an
http-equiv
attribute:
If a matching HTTP response header does not exist, warn
If a matching HTTP response header exists but
its value differs from the content
attribute value,
warn
Some tests refer to "CSS Style" information. Assemble the CSS Style by using the contents of:
the style
attribute of any element (use of the
style
attribute is deprecated in XHTML Basic 1.1
[XHTML Basic 1.1])
style
elements whose type
attribute is
"text/css", and whose media
attribute
is either not present or is present and contains values
"all" or "handheld"
(case-insensitive).
resources linked via link
elements and
xml-stylesheet
processing instructions, where:
the rel
attribute contains
"stylesheet" but not
"alternate" (case-insensitive)
the charset
attribute is either not present or
is present with value "UTF-8"
(case-insensitive)
the type
attribute is either not present or is
present with value "text/css"
the media
attribute is either not present or is
present and contains value "all" or
"handheld" (case-insensitive).
Note:
In the case of xml-stylesheet
processing
instructions, attribute in this section refers to
pseudo-attribute.
resources linked by CSS @import
at-rules whose
presentation media list is either not present or is present
and contains the value "all" or
"handheld"
In the course of assembling the CSS Style use only those CSS rulesets that are not restricted as to their presentation media type or whose presentation media type list contains "handheld" or "all".
Some tests refer to Included Resources, which are resources external to the resource being tested and yet vital to rendering that resource and whose URI has the "http" or "https" scheme, when represented in an absolute form. Examples include image and style sheet resources.
When retrieving resources, caching directives should be observed. Multiple references to cached resources are counted only once in regard of page weight (see 3.16 PAGE_SIZE_LIMIT ) and resource count (see 3.6 EXTERNAL_RESOURCES ).
Included Resources are defined as those that are referenced by the following:
the src
attribute of img
elements
the data
attribute of object
elements (see
notes below)
the href
attribute of link
elements and
xml-stylesheet
processing instructions as defined
in 2.4.6 CSS Style
images included by background-image
and
list-style-image
properties in the CSS Style (see
2.4.6 CSS Style)
@import
directives in the CSS Style - providing they
are unqualified as to presentation media type or qualified by
presentation media type "handheld" or
"all" (case-insensitive) as defined in 2.4.6 CSS Style
Note:
In some circumstances object
elements may act as synonyms
for other elements such as img
and iframe
. In
these cases it is noted in the relevant section when to regard object
elements as equivalents for other elements.
Note:
Resources that are retrieved as references from object
elements and whose Content-Type
HTTP header is not set to "image/jpeg" or "image/gif" are not considered to be Included Resources as discussed under 3.15.1 Object Element Processing Rule (i.e. objects that are "tasted" to determine their Internet content type but are then discarded are not Included Resources). Their treatment, as regards 3.16
PAGE_SIZE_LIMIT
and 3.6
EXTERNAL_RESOURCES
, is described in the relevant section.
Note:
Resources referenced by descendants of an object
element that itself refers to an Included Resource are not considered to be Included Resources as discussed under 3.15.1 Object Element Processing Rule (i.e. any img
or object
element which occurs in the fall-back of an acceptable object
element is not an Included Resource).
Linked Resources are resources linked to from the resource being tested (other than the resource itself), but which are not vital to rendering that resource whose URI begins with the "http" or "https" scheme when represented in an absolute form.
Linked resources are defined as those that are referenced by:
the href
attribute of a
(anchor)
elements.
the action
attribute of form
elements whose
method
attribute is not present or is present with
value "get" (case-insensitive).
Note:
Forms with method
attribute "POST"
(case-insensitive) are permissible in documents under test, but
are not checked by mobileOK Basic (posting might cause side
effects such as the addition of unwanted records to a
database).
Note:
When submitting forms use default values where supplied, otherwise supply empty values.
Several tests refer to the validity of aspects of a resource. This section defines specifically what this means.
A resource is considered a valid CSS resource if it conforms to
the grammar defined in [CSS Level 1], Appendix B. The presence of at-rules, properties or values or
combinations of properties and values that are not specified in
[CSS Level 1] does not constitute a validity failure
for CSS. See 3.21
STYLE_SHEETS_USE
for treatment of
such values. In addition, the @media
at-rule and
the presentation media list for the @import
at-rule are taken into account when evaluating CSS.
An image is a valid GIF image if it conforms to the grammar defined in section 25 of the [GIF] specification.
An image is a valid JPEG image if it follows the format defined in Annex B of the [JPEG] specification
A resource is considered to be valid UTF-8 if its bytes represent the valid UTF-8 encoding of some string, as defined in [RFC 3629], section 4
Several tests refer to white space. White space has the same definition in this document as in XML. For XML 1.0 [XML 1.0] it is defined in http://www.w3.org/TR/REC-xml/#sec-common-syn as being:
S ::= (#x20 | #x9 | #xD | #xA)+
i.e. the characters SP, TAB, CR
and LF.
This section describes tests for mobileOK Basic. Tests are organized alphabetically by the Best Practice from which they derive. Where a test derives from more than one Best Practice it is placed according to the one that occurs first in dictionary order.
This test does not determine whether the user is able to opt out of refresh.
If a meta
element is present with
http-equiv
attribute value of "refresh",
If the URI specified as part of the content
attribute is not the current resource's URI, FAIL
Else, warn
If a Refresh
HTTP header is present,
If the URI specified in the header value is not the current resource's URI, FAIL
Else, warn
The purpose of the test is to alert providers to the fact that their content may not be cached, if it would be beneficial to do so.
Note:
Where both a meta
element with http-equiv
attribute
and the corresponding HTTP header are found, the value of the HTTP header
must be used - see also note under 2.4.5 Meta http-equiv Elements.
If the HTTP response contains neither an
Expires
nor Cache-Control
header
If no meta http-equiv
element is present,
referring to those headers, FAIL
Continue the test using the value from the meta
content
attribute as though it were specified in the
appropriate header, warn
If a Cache-Control
HTTP header is present and
contains value "no-cache", or contains value
"max-age=0", warn
If a Pragma
HTTP header is present and
contains value "no-cache", warn
If an Expires
and Date
HTTP
header are present, and the Expires
header specifies a date
which is not later than what the Date
header specifies, warn
If any cache related header contains an invalid value, warn
If the HTTP response contains a Last-Modified
header,
Request the same URI again, adding an
If-Modified-Since
request header whose value matches that
of the Last-Modified
response header
If the HTTP response contains a Last-Modified
header and its value is again the same, and the HTTP response status is not
304 (Not Modified), warn
If the HTTP response contains an ETag
header,
Request the same URI again, adding an
If-None-Match
request header whose value matches that of the
ETag
response header
If the HTTP response contains an ETag
header
and its value is again the same, and the HTTP response status is not 304
(Not Modified), warn
The DDC is defined to support only UTF-8 encoding, and hence this test fails if a resource is not encoded in UTF-8. The test does not require that resource always be encoded in UTF-8; the test merely checks that the resource is available in UTF-8 encoding, if requested. Resources may be represented using other encodings where appropriate. This test verifies that a DDC-like device which only accepts UTF-8 encoding may access the resource in UTF-8 encoding.
This test requires that character encoding is explicitly specified and recognizes the following methods of specification:
HTTP Content-Type
header
application/xhtml+xml; charset=UTF-8
XML declaration
<?xml version="1.0" encoding="UTF-8" ?>
meta
element that is the first child of the document's
head
element, and whose http-equiv
attribute is "Content-Type", and whose
content
attribute specifies a character encoding
... <head> <meta http-equiv="Content-Type" content="application/xhtml+xml; charset=UTF-8"/> ...
If the HTTP Content-Type
header specifies a
character encoding other than UTF-8, FAIL
If the HTTP Content-Type
header does not
specify a character encoding:
If there is no XML declaration, or UTF-8 character encoding is not specified in the XML declaration, FAIL
If the HTTP Content-Type
header specifies an
Internet media type starting with "text/":
If there is no meta
element with
http-equiv
attribute that specifies UTF-8 character
encoding, FAIL
If character encoding is specified in more than one way, and not all values are the same, FAIL
If the document is not valid UTF-8 (see 2.4.9 Validity), FAIL
For each resource specified by 2.4.7 Included Resources:
Request the resource
If the HTTP Content-Type
header value of the
response starts with "text/" but does not specify UTF-8
character encoding, warn
Note:
In the following, an "html document" is a document that has "html" as its root element.
Note:
In the following, "regardless of its
stated DOCTYPE
" means that when
assessing validity against the XHTML Basic 1.1 and XHTML MP 1.2 DTDs this
may be carried out by inserting a DOCTYPE
if none is present,
or by replacing the given DOCTYPE
with the appropriate
DOCTYPE
for the DTD under test.
Note:
In the following, "a known XHTML version" means XHTML Basic 1.0, XHTML Basic 1.1, XHTML-MP 1.0, XHTML-MP 1.1 or XHTML-MP 1.2.
If the document's Internet media type, as specified in the
HTTP response Content-Type
header, is not
"application/xhtml+xml",
"application/vnd.wap.xhtml+xml", or
"text/html", FAIL
If the document's Internet media type is "text/html" or "application/vnd.wap.xhtml+xml", warn
If the document does not contain a DOCTYPE
declaration, FAIL
If the document is not an HTML document, FAIL
If the DOCTYPE
is not an XML
DOCTYPE
, warn
If the document is an HTML
document and it has an XML DOCTYPE
:
If the document does not declare the html namespace on its
html
root element, FAIL
If the DOCTYPE
refers to a known XHTML version, validate against that
DOCTYPE
and if invalid, warn
Otherwise (if the DOCTYPE
is not known), warn
If (regardless of its stated DOCTYPE) the document does not validate against the XHTML Basic 1.1 DTD:
If (regardless of its stated DOCTYPE) it does not validate against the XHTML-MP 1.2 DTD, FAIL
For each Included Resource (see 2.4.7 Included Resources):
If the response specifies an Internet media type that is not "text/css", "image/jpeg" or "image/gif", FAIL
If an image is required (see also 3.15 OBJECTS_OR_SCRIPT ) and the response specifies an Internet media type that is not "image/jpeg" or "image/gif", FAIL
If the Internet media type is "image/gif" or "image/jpeg", and the resource is not valid (see 2.4.9 Validity), FAIL
If a style sheet is required and the response specifies an Internet media type that is not "text/css", FAIL
If the Internet media type is "text/css" and the content is not valid CSS (see 2.4.9 Validity), FAIL
Note:
inputmode
is part of [XHTML Basic 1.1].
For each input
element with attribute
type
whose value is "text" or
"password" or whose type
attribute is
missing:
If the element's inputmode
attribute is
invalid according to Section 5.2 User Agent
Behavior of XHTML Basic 1.1 [XHTML Basic 1.1], FAIL
If the element's value
attribute is missing
or empty, and an inputmode
attribute is not present, warn
For each textarea
element:
If the element's inputmode
attribute is
invalid according to Section 5.2 User Agent
Behavior of XHTML Basic 1.1 [XHTML Basic 1.1], FAIL
If the element is empty and an inputmode
attribute is not present, warn
Retrieve the resource under test, and add the number of retrievals required to obtain the resource (see 2.4.4 HTTP Response) to a running total.
For each unique Included Resource, as defined in 2.4.7 Included Resources:
Request the referenced resource
Add the number of HTTP requests that are required to retrieve the resource (see 2.4.4 HTTP Response) to the running total. Include in the count only those objects retrieved under the 3.15.1 Object Element Processing Rule whose type
attribute is not specified, and those whose content type is either "image/jpeg" or "image/gif" irrespective of whether the type
attribute is specified.
If the total exceeds 10, warn
If this total exceeds 20, FAIL
The intent of this Best Practice is to avoid using transparent images for spacing. However, small transparent images are often used in e-commerce sites for user tracking purposes. The practice is common enough, and possibly vital enough to the business interests of mobile sites, that it is undesirable to fail sites that use such small transparent images. Therefore this machine-testable test merely warns about the presence of small (at most 2x2) transparent images and FAILs larger ones. It is believed that few if any sites would use transparent images of any significant size for tracking.
For each img
element and
object
element which is an Included Resource (see 2.4.7 Included Resources):
If all pixels are transparent,
If image height and width are both less than or equal to 2 pixels, warn
If either dimension exceeds 2 pixels, FAIL
If more than one image with all transparent pixels is present, warn
If an input
element with type
attribute set to "image" is present, FAIL
For each img
element and object
element which is an Included Resource (see 2.4.7 Included Resources):
If a usemap
attribute is present, FAIL
If an ismap
attribute is present, FAIL
Note:
The height
and width
HTML attributes specify pixels
when they are used as a number. No unit is specified.
For each img
element and
object
element which is an Included Resource (see 2.4.7 Included Resources):
If the height
or width
attribute
are missing, FAIL
If the height
or width
attribute
do not specify a size in pixels, FAIL
If the value specified by either the height or width attribute is greater than the corresponding dimension of the image, warn
If the value specified by either the height or width attribute is less than the corresponding dimension of the image, FAIL
Note:
404 and 5xx HTTP status do not result in failure when conducting this test.
Note:
The document body of linked resources is not examined.
For each linked resource, as defined in 2.4.8 Linked Resources:
Request the resource
If the Content-Type
header value of the HTTP
response is not one of the Internet media types listed in the
Accept
header in 2.4.3 HTTP Request, warn
If the Content-Type
header value of the HTTP
response does not specify a charset
parameter, or does but it
is not consistent with the value of the Accept-Charset
header
in 2.4.3 HTTP Request, warn
For each document internal reference (links in the document under test that refer to the document itself):
If there is no target for the reference or it is invalid (e.g. '#'), warn
Note:
The intrinsic size of images must be specified as attributes of the
img
element and not as CSS properties (see 3.9
IMAGES_RESIZING and IMAGES_SPECIFY_SIZE)
Note:
Only CSS Level 1 properties are considered in this test.
For each CSS Level 1 property in the CSS Style (see 2.4.6 CSS Style) whose value is a numeric measure of length stated together with a unit:
If the value is non-zero and the unit is not "em" or "ex" (and the value is not a percentage), and the property is not a margin, border or padding box property, FAIL
Note:
Extraneous white space characters in script and in CSS are not considered in this test. Such an extension may be considered in a future revision of this specification.
Count number of white space characters (see 2.4.10 White Space) in a sequence of more than one white space
character (not counting the first), which exist outside of a
pre
, style
, script
element, or XML
comment.
Add to this count the number of characters comprising XML comments. This total is the number of extraneous characters in the document.
Count total number of characters in document.
If the number of extraneous characters exceeds 10% of the count of characters in the document, warn
If the number of extraneous characters exceeds 25% of the count of characters in the document, FAIL
If the document contains a frame
,
frameset
or iframe
element, FAIL
This test does not determine whether the alternative text is meaningful.
Note:
An empty alt
attribute is acceptable and signifies that there is
no meaningful textual alternative, for example for images that are purely
decorative.
For each img
element:
If an alt
attribute is not present or
contains only white space, FAIL
This test does not determine whether the document is still usable without the objects or scripts.
If a script
element is present, warn
If any element has an "intrinsic event"
attribute (currently onload
, onunload
,
onclick
, ondblclick
, onmousedown
,
onmouseup
, onmouseover
,
onmousemove
, onmouseout
, onfocus
,
onblur
, onkeypress
, onkeydown
,
onkeyup
, onsubmit
, onreset
,
onselect
, onchange
), warn
For each a
and link
element:
If the value of the href
attribute begins
with the "javascript:" scheme, FAIL
If an applet
element is present, FAIL
Set the context to the root element and apply the Object Element Processing Rule
For each img
element that has no
object
element ancestor (other than the context node) in this context:
Treat this image as an Included Resource (and carry out appropriate tests).
For each object
element that has no object
element ancestor (other than the context node) in this context:
If the object
element is empty, warn
If the content of the object
element consists only of
white space, FAIL
If there is no type
attribute, warn
If it is not already cached (see 2.4.7 Included Resources), retrieve the referenced resource (ignoring the type
attribute)
If the Internet media type of the retrieved resource, as indicated by its Content-Type
HTTP header does not match that stated in the type
attribute, warn
If the Internet media type indicated by the Content-Type
HTTP Header of the retrieved resource is not "image/jpeg" or "image/gif", warn
Reapply this rule using the current object
element as the
context
Otherwise (the object is an acceptable image):
Treat this object as an Included Resource (and carry out appropriate tests), ignore img
and object
elements that are descendants of the current object
element.
Note:
A warning is issued when the Internet media type indicated by the type
attribute is not compatible with the Default Delivery Context because some user agents do not take into account the type
attribute of object
elements and this may cause the user agent to retrieve large incompatible objects with consequences to performance and cost.
Note:
An HTTP 406 status on retrieval of a resource referenced by an object element does not constitute a FAIL.
Retrieve the document under test, if its size (excluding any redirections discussed under 2.4.4 HTTP Response) exceeds 10 kilobytes, FAIL
Add to a running total (total size) the size of all the HTTP response bodies that are required to retrieve the document under test (2.4.4 HTTP Response).
For each unique Included Resource, as defined in 2.4.7 Included Resources:
Add the size of all the response bodies that are required to retrieve the resource (see 2.4.4 HTTP Response) to the running total. Include in the total only those objects retrieved under the 3.15.1 Object Element Processing Rule whose type
attribute is not specified, and those whose Internet media type as indicated by the Content-Type
HTTP header is either "image/jpeg" or "image/gif" irrespective of whether the type
attribute is specified.
If the total exceeds 20 kilobytes, FAIL
Note:
In the case of resources that are referenced more than once in the document under test, and where, as discussed under 2.4.7 Included Resources, they are cached, it is the initial retrieval of that resource (as determined by the first reference in document order) that counts towards the total.
Note:
Where the 3.15.1 Object Element Processing Rule yields a resource that is found to be cached, objects that must be assessed in the course of yielding the cached resource count towards the total.
This test does not determine whether the title is meaningful.
If a title
element is not present in the
head
element, or is empty, or contains only white space
(see 2.4.10 White Space), FAIL
For each a
, link
,
form
, and base
element:
If a target
attribute is present,
If its value is not one of "_self", "_parent", or "_top", FAIL
For each radio button group within a form
element (input
elements with type
"radio" that share the same name
attribute
value):
Check that exactly one input
element within
this group has its checked
attribute set to
"checked", and if this is not the case, warn
For each select
element:
If there is no nested option
element whose
selected
attribute is set to "selected",
warn
If there is more than one option
element
whose selected
attribute is set to
"selected", and the multiple
attribute is not
set to "multiple", warn
If the CSS Style (see 2.4.6 CSS Style) contains rules referencing
the position
, display
or float
properties, warn
This test looks for elements in the Text Extension module defined by [XHTML Modularization], some of which are not supported in XHTML Basic [XHTML Basic 1.1]. It also looks for commonly-used elements and attributes that were deprecated in HTML 4, and are not supported, or are deprecated, in XHTML Basic.
Note:
This test does not require that any CSS Style is used, since in some cases, no presentation information is required at all (for example, a simple page of text).
If the document contains any basefont
,
bdo
, center
, del
,
dir
, font
, ins
, menu
,
s
, strike
or u
elements, FAIL
If the document contains any b
,
big
, i
, small
, sub
,
sup
or tt
elements, warn
If any element has a style
attribute, warn
If all styles are restricted to presentation media types other than
"handheld" or "all" by means of @media
at-rules, warn
If the CSS Style contains at-rules (other than the
@media
at-rule, and the presentation media type list of the
@import
at-rule), properties, or values that are not recognized
as being specified in CSS Level 1, or if the value of a recognized CSS Level 1 property is incompatible with the property, warn
If a table
element exists, warn
This test does not catch all cases where tables are used for layout purposes.
For each table
element:
If it contains at most one tr
element, FAIL
If no tr
element contains more than one
td
element, FAIL
For each nested td
element:
If the element contains only an image (or equivalent object) whose actual dimensions are 2x2 or less, FAIL
For each table
element:
If it contains a table
element, FAIL
The editors would like to thank members of the BPWG for contributions of various kinds.
The editors acknowledge significant written contributions from:
This appendix lists all Best Practices and indicates whether each has a corresponding test in mobileOK Basic.