The development of other explicit namespace attributes in DocBook 5.2

["John L. Clark" <john.l.clark@gmail.com>]

I've noticed in The Definitive Guide (and in the schema) for DocBook
5.2 that this version allows "[a]ny attribute in any other explicit
namespace" on any element[0, 1]. I'm excited about this development,
as I think it will be good for expressive extensibility that still
maintains a light touch on the overall structure of documents. (One
early use case I have for this is to flag an element as fit for
replacement with a command in LaTeX output. I'm currently using the
`role` attribute for this in DocBook 5.1, and I feel uneasy about it.)

It seems that this is an innovation that happened between DocBook 5.1
and DocBook 5.2, and I am curious to read the discussion around this
development. Does anyone know where I can read about the work that the
TC did in coming up with this enhancement? (Maybe on the mailing list
somewhere? It's a bit hard to search.) Also, I don't see this change
listed in The Definitive Guide[2], but it seems valuable enough to
list as one of the major changes. What do you all think about listing
it there?

I continue to be grateful for all of your work in continuing to
maintain DocBook! I'm looking forward to 5.2 stabilizing soon!

Peace,

    John L. Clark

[0] <https://tdg.docbook.org/tdg/5.2/ref-elements#common.attributes>
[1] <https://docs.oasis-open.org/docbook/docbook/v5.2/cs01/rng/docbook.rng>,
in "db.common.base.attributes"
[2] <https://tdg.docbook.org/tdg/5.2/ch00-online#changes-in-52>