PAL

Ptolemaeus Arabus et Latinus

_ (the underscore) is the placeholder for exactly one character.
% (the percent sign) is the placeholder for no, one or more than one character.
%% (two percent signs) is the placeholder for no, one or more than one character, but not for blank space (so that a search ends at word boundaries).

At the beginning and at the end, these placeholders are superfluous.

combination, connexion, union, junction (LSJ)/ application R ‘combination’

English

References: TB Robbins: 113
Translation of:
Greek: συνάφεια [TB Robbins: 1:24 Τ, 52]