I'm looking into filtering a GFF3 file I generated from GMAP. Looking online it's clear that there isn't a universal way to filter GFF3s, but the score (column 6) seems to be commonly used. I would like to understand what the score means before setting a threshold for filtering. However, there isn't a universal format for the score (GFF3 specifications) and the GMAP manual doesn't explain the GFF3 format.
What is the value in the score column?