The State of Florida in 1998, in order to fight disparity in sentencing, created a "scoring system"[0] where every crime in Florida is given a number that corresponds to the number of months in prison that crime could carry.
The scoring system is byzantine as all hell and I challenge anyone to figure it out.[1]
"Scoring out" is simply a term used by Florida convicts to explain how much time they got among themselves I guess. Maybe it was inappropriate to use it here.
Gain-time is a sentence reduction scheme where people get time off their total sentence for staying out of trouble.
[0] http://macklawpa.com/criminal-defense/felony-score-sheet/
[1] http://www.dc.state.fl.us/pub/sen_cpcm/cpc_manual.pdf
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