I'm doing my first mkiv index (it took me a long time to upgrade from
mkii!) and I really like the processor feature to format elements
differently. But there are a couple of things I would really like to
achieve that I'm struggling with:

   1. Elided numbers in an index range entry. For example if I have a
   \startregister - \stopregister pair resulting in an index entry like

   entry 354--356

   I would like to be able to make this read

   entry 354--6

   There are different conventions for number span elision but usually
   teens aren't elided so

   entry 314--316

   would become

   entry 314-16.

   It strikes me that if I could set up a processor specifically for page
   number ranges I could possibly write a macro to do elision; but I don't
   think that's currently possible? Maybe it's possible in lua to write code
   which both identifies range page numbers and carries out the elision. I'm
   not quite sure where to start.

   2. Fine tuning column and page breaking in an index. This is tricky,
   because there are usually very few "good" places to break an index, and
   automatic breaking seems to alter slightly depending on whether
   interactions are set up or not, but is there a way to manually insert a
   column or page break into the register before or after a certain entry, the
   way there is for a table of contents?

Sorry for no MWE, for obvious reasons. Any pointers to what might be able
to be done on these would be much appreciated.

Thanks.

Duncan