[dev-biblio] configuring grouping

I have now just realised that this means that not only do users need
to be
able to specify the groupings for the bibliography (primary and
secondary,
and any others) but that user needs to be able to specify which group
the
citation belongs to for each paper!

Not following here. Can you explain?

Sorry Bruce this seems to make a bit more difficult.

Crap!

OK, but let’s see if we can make this as simple as possible. I have
learned through working on citeproc and csl that often one can find
simple solutions to what at first seem like difficult problems.