  We discuss BRST and anti--BRST transformations for an Abelian antisymmetric
gauge field in 4D and find that, in order for them to anticommute, we have to
impose a condition on the auxiliary fields. This condition is similar to the
Curci-Ferrari condition for the 4D non--Abelian 1-form gauge theories and
represents a consistency requirement. We interpret it as a signal that our
Abelian 2-form gauge field theory is based on gerbes. To support this
interpretation we discuss, in particular, the case of the 1-gerbe for our
present field theory and write the relevant equations and symmetry
transformations for 2-gerbes.
