I'm trying to find documentation on how to write PMCs. I can find lots of
PMCs in the source tree, but I can't seem to find documentation on how to
go about writing them, or what the various fields and flags do.

For example, the string PMC_data occurs in many source files, but as far
as I can tell nowhere in any documentation files, and there aren't many
comments about it in include/parrot/pobj.h

I don't find any documentation saying "if you do this you'll need to do that
in a destructor else you'll leak".

Am I missing something obvious?

Nicholas Clark