  We describe constraints that need to be satisfied ``near the top'' of the
portraits of the elements in Grigorchuk group. These constraints, if satisfied
by the portraits of all sections of some binary tree automorphism, guarantee
that this automotphism belongs to the closure of Grigorchuk group in the
pro-finite group of binary tree automorphisms. The constraints may be viewed as
an effective version of a more conceptual description given earlier by
Grigorchuk.
