"1/2" was used for some Asian game at least in California. The player would receive back 1/2 of what he bet. I think the game also could pay zero, 1 (your bet returned) or 2 (double your money back). Offhand, I don't know the name of the game. Pretty sure I posted a scan of a 1/2 chip on ChipBoard somewhere but can't remember which casino it was!