Quote Originally Posted by Medved View Post
I don't quite understand what you meant by "a verb with incomplete declension, impersonal only?"
A verb has conjugation (спряжение), a noun has declension (склонение). We conjugate verbs, and we decline nouns.
So, it should read "a verb with incomplete conjugation".

Yes, it is incomplete:

надлежу impossible
надлежишь impossibble
надлежит OK

надлежим impossible
надлежите impossible
надлежат impossible

present tense: Мне (тебе, ему, ей, нам, вам, им) надлежит.
past tense: Мне (тебе, ему, ей, нам, вам, им) надлежало.

It is impersonal only, it cannot have a grammar subject in Nominative.

Usage: Dative (to whom) + надлежит (надлежало) + infinitive (to do something).