The generalized NSCL BUFREAD subroutines has a mask that it will check against the bitmask of an event before decoding it. If none of the bits in the event bitmask that correspond to the set bits in the BUFMASK mask is set, then the event is rejected and BUFRFAAD will go to the next event. This command allows you to change the BUFFMASK mask to the desired value. This command is especially useful and speed up analysis when only a special portion of the data on tape is desired.

The program will first display the present value of the BUFMASK.

‘Input mask in hex (def=no change)’ asks for the new mask value in hexadecimal format. If a return is given, then the present BUFMASK value will remain.