A symbol used to denote unknown configuration at a
chiral centre.
Source:
PAC, 1984, 56, 595
(Nomenclature and symbolism for amino acids and peptides (Recommendations 1983))
on page 601
Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
doi:10.1351/goldbook.
