Page numbers are always numbers?

It _appears_ from at least a first walk-through of
this specification that page numbers are implicitly
only numbers.  Yet for many of the documents that I
work with, page numbers are often NOT simple numbers.
Instead, many have prefixes, and some have embedded
formats (such as lowercase roman) instead.

For example, the first appendix (A) might have page
numbers A-1, A-2, etc.; the second appendix (B) might
have page numbers B-1, B-2., etc.  An executive summary
might be ES-1, ES-2, etc.  The front matter would be i, ii,
iii, iv, etc.

These should be "built into" the page numbers, so that
cross-reference ("see page X") and automatically
generated tables of contents would work correctly.
The appendix numbers should be automatically generated
too, to the extent that swapping Appendix B and D would
renumber the new B and D correctly.

Yet I can't see how this format would do this.
Am I missing something?

--- David A. Wheeler