WAI: Web Accessability Inititative Guidelines
Many of the WAI guidelines can be turned into a schema easily. Here is the schema, and here is an evil test file. And here is the result, as generated by schematron-report. This is an unusual schema, because it is not a definitional schema, but rather a best-practise schema.
Of course, any HTML in XML file or XHTML file can be used for data. The test file is certainly not good or even valid HTML (against the HTML DTDs). But you can see that this WAI schema does not require documents that are valid; it only is interested in validating the patterns that WAI is interested in. (Actually, I have just made each section in the WAI guidelines into a pattern: this perhaps is slack, since really a pattern should be a bunch or rules that are somehow interconnecting.)
Here is the same schema and document represented in RDF.
Copyright (C) Rick Jelliffe, Academia Sinica Computing Centre. The Schematron software and this page are available for any public use, under the conditions of the GPL or MPL, but please mention our names in any documentation or About screens for any products that uses it. Comments, fixes and upgrades welcome: email firstname.lastname@example.org