The flat trace cut is based on logged NCD signal and is coded as a SNOMAN hard-wired cut "flt_flattrace_cut.for". The parameter for this cut can be found in "filter_flth.dat" :
*DO FLTH 33 -i(30I -I) #. FLTH: flat trace Cut #. 19750101 0 20380517 03331900 6*0 #. Standard Database Header 19750101 0 20380517 03331900 16*0 #. 5 #. threshold on flat trace
A event is tagged as a flat trace event if the difference between the minimum value and the average value of the trace is less than 5 (or the first parameter in FLTH).
To use this cut, one can put a call flt($flattrace_cut) in the programmable event loop. The cut returns "true" if the event is a good event.