weapon type vs. weapon category

[Bandobras]

Does anybody know what is the relation between animation type, weapon type and weapon categories? E.g. how is

http://ufo.myexp.de/wiki/index.php/Modelling#Animation

"biggun" related to

http://ufo.myexp.de/wiki/index.php/UFO-Scripts/weapon_%2A.ufo

type "biggun" and category "3"?

They seem to be related, but they differ for some weapons in human_weapons.ufo...

I would like to document it in the wiki, but nobody seems to know...