Why Amateur satellite operators use single-letter band designators borrowed from radar/microwave nomenclature: H is 15 m, A is 10 m, V is 2 m, U is 70 cm, L is the 1.2 GHz band (23 cm), and S is the 2.4 GHz band (13 cm). So a satellite listed as mode L/S takes a 23 cm uplink and delivers a 13 cm downlink. These letters appear in satellite mode listings like U/V or L/S, describing the uplink and downlink bands.
Watch out The 2 m and 70 cm bands are designated V and U, not L and S; and the letters say nothing about sideband choice or the type of digital system carried.
L is Long wave of the microwaves (23 cm), S is Shorter (13 cm). V/U = 2 m/70 cm, L/S = 23/13 cm.