Salts or esters of carbamic acid, H2NC(=O)OH, or of N-substituted carbamic acids: R2NC(=O)OR', (R' = hydrocarbyl or a cation). The esters are often called URETHANE or urethan, a usage that is strictly correct only for the ethyl esters. (From IUPAC [Internet]. International Union Of Pure And Applied Chemistry; c1995 [updated 2004 Jan 9; cited 2004 May 3]. Available from http://www.chem.qmul.ac.uk/iupac/class/oneN.html#35/).