Sixteenth index from the start of the figure.
The meter the figure is counted in, in any form that names one. Asked for rather than defaulted: the built-in figures are written on a 4/4 grid, but a caller working in 7/8 who leaves it out has no way to hear that the ranking they got was somebody else's bar.
The weight, 0 to 4.
How strongly a position on the sixteenth grid is felt, from 4 (the downbeat) to 0 (an off sixteenth).
This is the ranking the thinning rule works down: the notes a player drops first when asked for something easier are the ones carrying the least of the metre. The ranking is the meter's own — metricWeight says which positions are the downbeat, a secondary strong pulse, and a plain main pulse, and the two ranks below them are the pulse's first subdivision and everything off it. In 4/4 that is the downbeat, the half bar, the other quarters, the quavers and the semiquavers; in 6/8 it is the two dotted-quarter pulses, then the quavers, and the quarter-note positions a 4/4 reading would rank above them fall where they belong, between the beats.