the stereochemical descriptor in the systematic name is written in lower-case italics rather than upper-case italics as for regular chiral atoms. D-, L- See: Fischer projection The stereoscriptors D- (from Latin dexter, right) and L- (Latin laevus, left) are used to describe the configuration of α-amino acids and sugars. First, the three-dimensional molecule must be transformed in a defined notation as a two-dimensional image ("Fischer projection"). For this, the C atom with the highest priority according to the normal nomenclature rules is arranged on top and the further carbon chain is arranged vertically underneath. The chiral C-atom most remote from the group with the highest priority is used for the assignment of D- or L-. If the residue located on this carbon atom (usually an OH group) points to the left, the molecule originates from the L-series. If the residue points to the right, the descriptor D- is used. The descriptors D- and L- are written as small capitals and separated by a hyphen from the rest of the name. d-, l- Sometimes the small capital D- and L- stereodescriptors mentioned above are mistakenly confused with the obsolete italic d- and l- stereodescriptors, which are equivalent with dextrorotatory and levorotatory optical rotation, i.e. (+)- and (−)- stereodescriptors, respectively. See also Molecular descriptor Goldschmidt tolerance factor Geminal Vicinal (chemistry) References Chemical nomenclature