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.

Gemini ‘Gemini’

English

References: Alm. Toomer: 94; 94; 100-103; 364-5
Translation of:
Greek: Δίδυμοι [Alm. Heiberg: II.7, 124:12; II.7, 124:16; II.8, 134-140; VII.92-95]