On the background of a careful analysis of nonlinear DAFs, linearizati
ons of nonlinear index-2 systems are considered. Finding appropriate f
unction spaces and their topologies allows to apply the standard Impli
cit Function Theorem again. Both, solvability statements as well as th
e local convergence of the Newton-Kantorovich method (quasilinearizati
on) result immediately. In particular, this applies also to fully impl
icit index-1 systems whose leading nullspace is allowed to vary with a
ll its arguments.