For f a meromorphic function on the plane domain D and
a ∈ [Copf ], let Ēf(a) =
{z ∈ D[ratio ]f(z) = a}. Let [Fscr ] be
a family of meromorphic functions on D, all of whose zeros are of
multiplicity at least k. If there exist
b ≠ 0 and h > 0 such that for every
f ∈ [Fscr ], Ēf(0) =
Ēf(k)(b) and
0 < [mid ]f(k+1)(z)[mid ] [les ] h
whenever z ∈ Ēf(0),
then [Fscr ] is a normal family on D. The case
Ēf(0) = Ø is a celebrated
result of Gu [5].