masking out correlator crates, e.g., export CORRSRCMASK=0x00000ff (the variable is a group of 8 hex-charactrer bit-masks, one for each of the 4-board “segments”, where everything is counted from 0 from right to left – the example says to use all of crate 0 only; CORRSRCMASK=0xff0600c0 would mean use all of crate 3, boards 1&2 in crate 2, none of crate 1, and boards 6&7 of crate 0.)