An alternative convention for solving the ambiguity problem of (3+1) superspace group symbols

An alternative convention is proposed for solving the ambiguity problem of (3 + 1) superspace group symbols described by Yamamoto, Janssen, Janner & de Wolff [Acta Cryst. (1985), A41, 528-530] based on the requirement that the condition for equivalence of modulation vectors to be independent on a selection of basis vectors is satisfied.