configuring page number prefixes

I was just working on a style file for APA, and came across an oddity
that requires adding an attribute somewhere.

When I looked at examples of APA, I thought I was seeing a really oddly
designed style with a lot of inconsistencies. For example, a journal
article will render pages like “23-43” while a magazine may do “pp.

It turns out on deeper inspection there is a more general logic. If a
record would typically have a volume and/or issue number (some kind of
article), but doesn’t, then the prefix gets added.

This leads me to think that I want to configure this like so:

   <locator unit="page" use-when="missing-volume-issue">
       <single>p. </single>
       <multiple>pp. </multiple>

Any thoughts, contrary opinions, etc.?