Pretty sketchy, but some there is some info at 5-H-1 & 2. One important item not mentioned anywhere is it's a 12 hour call out, just like a trip. Right back on LSR when it's over if not used, no different from any other assignment. Something to consider is the 60 minute report time (30 minute for DH) in the FOM. Not sure if it applies on FSB (does the "report time" clock begin at the start of the FSB or when the trip assignment is made?).