Thanks iCake

Another couple of examples of 2. -

худ|ой (~, ~а, ~o) no ~ы but i assume this exists - худы e.g. студенты худы?
цен|ный (~ен, ~на) no ~но or ~ны but i assume e.g. эти ценны is possible?

But I get the general idea. Most likely the dictionary only gives forms which it considers irregular or which cannot be inferred.

Thanks for expanding xXHoax's point about which ones can have a short form. I guess the main point is that in most cases it will just work out alright from the sense - i.e. unconsciously I would not try to use adjectives other than qualitative ones in a short form. Also - I think (according to my grammar book) short adjectives are "bookish" - that is not used so much in speech?

спасибо болшой