Contents.

1. Generalities.
2. List of main programs with general description.
3. Instructions for use of individual programs.
4. The shell program "cohomology".
5. Examples:
   a) Computation of 2-part of multiplier of m21=PSL(3,4).
   b) Computation of H^2(SL(3,5),M), (M=natural module).
   c) Computation of H^2(SL(5,2),M), (M=natural module).
   d) computation of a presentation of the nonsplit extension of SL(3,2) on
      its natural module, using a given presentation of SL(3,2).
6. Other programs.
7. Formats of PCP files.
