In the case of stereoselectivity, the absence of selectivity is trivially defined as a 1:1 ratio between two stereoisomers. This is sound in the case of enantiomers that both have the same thermodynamic stability, but this is an arbitrary decision in the case of diastereomers as these isomers display different relative stabilities, and a diastereomeric excess (de) of 0% is thus unexpected under any condition.