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.

George of Trebizond, Commentarii et expositiones in aphorismis Libri fructus Ptolomei

Paris, BnF, lat. 7309 · 31r

Facsimile