In morpheme-based morphology, the term null allomorph or zero allomorph is sometimes used to refer to some kind of null morpheme for which there are also contexts in which the underlying morpheme is manifested in the surface structure.
In addition, according to some linguists such as Radford, in children's language the forms of many auxiliary verbs such as do have null allomorphs in tenseless clauses such as Teddy not go.
Null allomorphy occurs a lot in the grammar of the German language.
The singular form of the dative case of masculine and neuter nouns such as der Mann (the man) has an optional grammatical suffix -e: dem Mann-e.
Many Dutch compound words have an interfix -s which is completely optional: both doodkist and doodskist ("coffin") are possible, as it is the case with spellingprobleem and spellingsprobleem ("spelling problem").