Ammonium oxalate, C2H8N2O4 - sometimes written as (NH4)2C2O4 - is an oxalate salt with ammonium (sometimes as a monohydrate). It is a colorless salt under standard conditions and is odorless and non-volatile
A 2255 (OTTO) Ammonium oxalate, 99% Cas 6009-70-7 - used for the detection of calcium, lead, fluoride and a buffering agent.