Not sure which part you're alluding to, but the number of days off that reserves get is based on the reserve guarantee for that month. Then, if there is at least 20% reserve coverage, all reserves in a category get an additional day off.

A's = captain positions, B = First Officer position.

SLIs = Seniority List Instructors, in other words sim guys who are hired from the line to teach, as opposed to hiring non-seniority list instructors who are not pilots on the seniority list and cannot fly the line.