金剛般若波羅蜜經註解 1.6

1.6

經者，訓法、訓常。梵語修多羅，此翻契經，謂契理、契機故也。

As for 'sūtra' (jing), it glosses both 'standard' (fa) and 'constant' (chang). In Sanskrit it is 'sūtra', translated here as 'tallying scripture' (qijing), meaning that it tallies with principle and tallies with capacity.