I would like to use a customized page numbering scheme. Each chapter has an abbreviation that it uses and I would like that to be part of the page number format.
Example: Chapter 1 is "United States of America (USA)" I use a variable for the USA abbreviation called "Abbrev" and can use that same variable on the master page so that the page numbering system for that chapter will be USA-1, USA-2, etc. Is it possible to bring in that same numbering system into the TOC? Can the TOC reference page use a user-defined variable?
As far as I know, there's no way to use a user-defined variable in either the TOC reference page or as part of an autonumber scheme.
If you have the page number in its own paragraph (that is, nothing but <abbrev>-<$curpagenum> in there) with its own paragraph tag, you might be able to use the <$paratext> building block in the TOC reference page to bring it in, I'm not sure if it would be <$paratext> by itself or maybe <$paratext>-<$pagenum>.
<$paratext[paratag]> construct be used in the RefPage expressions?
No, you can't use a building block that calls other paragraph tags within a TOC.
I can think of two approaches—the first is to use the chapter number building block on the reference page, i.e.,
<$chapnum>–<$pagenum>. Then designate the chapter number as Text, and set the number to USA for chapter 1, France for chapter 2, etc. Then update the book and the text values will preceed the page numbers. Obviously, if you are already using the chapnum building block for traditional chapter numbers, this one won't work.
USA-1, USA-2, USA-3
France–1, France–2, France–3
The second option is to create the TOC not using the TOC feature, but as a series of X-refs, which can call in variables. It's more work to set up, but once done, it looks the same as a traditional TOC to the reader and it's as easy to update as a generated TOC.
I had never even looked far enough down to see you could use Text! That is cool.
The text feature is used to ID chapters in the running heads and in the generated files that don't use traditional numeric chapter numbers. More typically something like this (written out or abbreviated):