Stating conformance in RDF

Please note that this work is being superseded by the EARL project.

This outlines an RDF scheme for expressing conformance to a requirement (for example, whether a document conforms to the XHTML specification, or whether a particular element in a page conforms to a particular checkpoint in WCAG). This is a bit of work done by Dan Brickley and Charles McCathieNevile. There is also a proof-of-concept implementation that (hopefully) works in javascript-enabled browsers.

There are several properties included here:

A resource's conformance to another resource can be as follows:

• meets: The resource being tested conforms to the requirement which is the other part of the triple
• fails: The resource does not meet the requirement.
• notApplicable: The requirement is not applicable in this case.
• okfor: This means that either the resource meets the requirement, or the requirement is not applicable. Although this can be inferred and is therefore not strictly necessary, it is useful in collecting information.
• unknown: It is not known whether the requirement is met or not. In some cases, this can be useful information, since it may not be the default condition.

This can be expressed visually as follows (if your browser does not support the use of mixed namespaces to include SVG, you might get a text representation again):

There are some more properties, that are included because this was designed specifically for WAI specifications

meets1, meets2, meets3

The WAI specifications define three different levels of conformance. For some requirements, it is possible to conform at different levels. In using these it then needs to be determined whether conformance to level 2 includes conformance to level 1 (as with WAI specifications) or whether on resource actually specifies several types of conformance. (Should this change? Level of conformance should be some kind of atomic thing (a number?) for dealing with places where we don't know anything useful like a URI???) This is particularly important for the , where there are a number of checkpoints with relative priority - to which it is possible to conform at several levels.

A code example

The following piece of RDF uses this scheme to assert that this document meets the requirements for level-A conformance for Web Content Accessibility Guidelines 1.0, and conforms to the CSS2 specification:

<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
         xmlns:conform="http://www.w3.org/1999/11/conforms/#">
  <rdf:Description about="Overview.html">
    <conform:meets1 rdf:resource="http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505"/>
    <conform:meets rdf:resource="http://www.w3.org/TR/1998/REC-CSS2-19980512"/>
  </rdf:Description>
</rdf:RDF>

How to use it

This scheme can be used to assert that any objects conforms to any requirement, so long as the requirement and the object both have a URI. For example, each checkpoint for each of the 3 WAI Accessibility Guidelines specifications has a URI.