I vaguely remember that REXX book ('twas the one with a playing card
on the front, no?), but I also don't recall how it differentiated
text that was intended for one track from the other.
But more importantly, it is *very* important that a conforming use
of TEI be allowed to add attributes and elements to the vocabulary.
My take on reality is that a lot of people out there in the world
would prefer to avoid doing so. I'm not sure if that's because they
find using ODD too hard (and if so is that because our documentation
is not good enough), or don't want to deal with multiple namespaces,
or think no one will like them (particularly their funding body) if
they add something to their schema. But rest assured, it is a normal
and accepted practice.
(Of the half-a-dozen or so main TEI customizations we use at the WWP,
three have added elements or attributes.)
> Tw similar examples from the 20th century: when the programming
> language REXX was introduced for IBM mainframes, at least one of
> the manuals (probably the User’s Guide) explicitly marked two
> reading paths, one for the first reading covering key concepts and
> avoiding some details, the other (a superset of the first, if I
> remember correctly) including discussions of details and less
> crucial topics. I no longer recall how the two were distinguished
> (arrows and instructions to skip to section n.m? or type size? or
> And the TeX and LaTeX books explicitly mark some material with a
> ‘dangerous curve’ icon to signal that it may safely be skipped for
> introductory purposes.
> Like Martin (Holmes), I see that this could be captured with divs
> and a strong stomach for a very broad interpretation of div. Like
> Martin (Mueller), I think I’d rather use an attribute on p (or two
> distinctive element types); it doesn’t feel at all div-like to me.
> My instinct would be to say this is a good example of why it’s
> important that conforming uses of TEI be allowed to add attributes
> and elements to the vocabulary, but I have the impression that not
> everyone agrees that extending the Guidelines should be a normal
> and accepted part of using TEI. (TEI P3 was itself a conforming
> instance of TEI P3, which extended and modified the vocabulary
> slightly as a way of underscoring the point that extensions and
> modifications are not shameful or undesirable. At least, that was
> what at least one of the editors thought and said.)