Lars, David

I don't mind either way and happily leave the decision to David but one
question:

 > Compare with the case for the NFSS fontdef tokens. I understood the meaning
 > of e.g. \T1/pad/m/n/12 (when TeX was showling an hlist) the first time I
 > looked at it, but it took several months before I realised how tricky it
 > really was.

how tricky was what?

are you saying that the decision within NFSS was good or bad? I mean it
disallows / as part of a name but it resulted in (given the length) quite
readable names, didn't it? and in practice the use of / did not result in any
practical problems (or does the above statement mean you tried to call a
family something/something and then noticed that this is not working?)

so perhaps using / for separation so that you get

 \TP@I/frontmatter/heading/section

might be an option too. it would have the advantage of splitting csnames in
their parts is a bit simpler.

frank