  An element $g$ of a group is called {\em reversible} if it is conjugate in
the group to its inverse. This paper is about reversibles in the group $G$ of
formally-invertible pairs of formal power series in two variables, with complex
coefficients. The main result is a description of the generic reversible
elements of $G$. We list two explicit sequences of reversibles which between
them represent all the conjugacy classes of such reversibles. We show that each
such element is reversible by some element of finite order, and hence is the
product of two elements of finite even order. Those elements that may be
reversed by an involution are called {\em strongly reversible}. We also
characterise these.
  We draw some conclusions about generic reversibles in the group of
biholomorphic germs in two variables, and about the factorization of formal
maps as products of reversibles. Specifically, each product of reversibles
reduces to the product of five.
