  We analyze the BRST cohomology of the critical N=2 NSR string using chiral
bosonization. Picture-changing and spectral flow is made explicit in a
holomorphic field basis. The integration of fermionic and U(1) moduli is
performed and yields picture- and U(1) ghost number-changing insertions into
the string measure for n-point amplitudes at arbitrary genus and U(1) instanton
number.
