WCAG 2 is nearly consistent in pretending that Web standards do not exist (with one curious exception that I'll get to shortly). Some teenagers have greater understanding of valid, semantic markup than the Working Group does, as evinced in passages like these:
Information that is conveyed by variations in presentation of text is also conveyed in text, or the variations in presentation of text can be programmatically determined.
Now, what does ""presentation"" mean? Really?
Doesn't the requirement to convey the information in text make it possible to write instructions for an online form as follows?
* Fields marked in red are required.
* Fields marked in green are optional but recommended.
I have just ""conveyed"" the colour differences. (It so happens that the colours are exactly the rare ones that are confusable to colourblind people.)
If I am using markup to vary presentation of text, as one typically will (how else do you do it if you aren't using a picture of text?), how is that markup ever not programmatically determinable? The browser had to read it to vary the presentation in the first place. All the usual elements, like em, strong, b, i, and u, are understandable by a machine. So is CSS, even at the simple level used in this document as a demonstration (span class=""red"" or =""green""). More complex CSS selectors, like :last-child, are also programmatically determinable.
In essence, for any author using markup, even lousy presentational markup, how is it possible to flunk this criterion?
SC 1.3.1 and 1.3.4 have been combined to read "Information and relationships conveyed through presentation can be programmatically determined or are available in text, and notification of changes to these is available to user agents, including assistive technologies." This wording is similar to the wording of SC 1.3.4 at the time of the comment, but the success criterion is clear that it is the _information_ conveyed by variations in presentation that must be conveyed, not the _fact_ that such information exists as the example in the comment suggests. The How to Meet document for the combined Success Criterion has been expanded to make this clearer.