omissible

The locative preposition is normally not omissible except when the Ground where the Figure is localized is inherently locative such as ka-sc 'land, ground, earth' and/or relates to the stereotypically expected location of the Figure such as di-yo 'house, room' or ka-to 'sky, heaven'.

Adjuncts are usually freely omissible, but in Awa Pit and Songhai the omission is mandatory.

In the following example, I have put square brackets around omissible material (as usual, any of the noun phrases are omissible on their own):

The adverb taare is omissible only when the copula naa is followed by a locative adverb, as in: yanaa can (taare) da baakii 'he is there (together) with the guests'.

In English (and also at least in Swedish, German, and Finnish) the Benefactive/Source is freely omissible, which means that three of the four roles are conceptually prominent.

Note furthermore that it is the symmetric preposition with that tends to be omissible in connection with reciprocal constructions of certain verbs.