  In the recent years, a number of issues concerning distributions generating
1- flags (called also Goursat flags) has been analyzed. Presently similar
questions are discussed as regards distributions generating multi-flags. (In
fact, only so-called special multi-flags, to avoid functional moduli.) In
particular and foremost, special 2-flags of small lengths are a natural ground
for the search of generalizations of theorems established earlier for Goursat
objects. In the present paper we locally classify, in both C{\omega} and C
\infty categories, special 2-flags of lengths not exceeding four. We use for
that the known facts about special multi-flags along with fairly recent notions
like strong nilpotency of distributions. In length four there are already 34
orbits, the number to be confronted with only 14 singularity classes - basic
invariant sets discovered in 2003. As a common denominator for different parts
of the paper, there could serve the fact that only rarely multi-flags' germs
are strongly nilpotent, whereas all of them are weakly nilpotent, or
nilpotentizable (possessing a local nilpotent basis of sections).
