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.

Mercure ‘Mercury’

French. – Grammar: n.

References: PH Morelon: I.7:1, 22:16; I.10:1, 32:2
Translation of:
Arabic: عطارد [PH Morelon: I.10:1, 33:2]
Arabic: كوكب عطارد [PH Morelon: I.7:1, 23:15]