  We consider an extension of the Coulomb gas picture which is motivated by
Liouville theory and contains negative powers of screening operators on the
same footing as positive ones. The braiding problem for chiral vertex operators
in this extended framework is analyzed. We propose explicit expressions for the
R-matrix with general integer screening numbers, which are given in terms of
4F3 q-hypergeometric functions through natural analytic continuations of the
well-known expression for positive integer screenings. These proposals are
subsequently verified using a subset of the Moore-Seiberg equations that is
obtained by simple manipulations in the operator approach. Interesting new
relations for q-hypergeometric functions (particularly of type 4F3) arise on
the way.
