SRFI:s
From Gambit wiki
SRFI
Scheme Request For Implementation. See http://srfi.schemers.org/.
Gambit natively implements the following SRFIs: 0, 4, 6, 8, 9, 18, 21, 22, 23, 27, 30, 39, and 88.
Black Hole includes several additional popular SRFIs, including 1, 13, 14, 16, 19, and 95, while others may be downloaded from Snow.