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.

la sphère des étoiles fixes ‘the sphere of the fixed stars’

French

References: PH Morelon: I.5:3, 20:26
Translation of:
Arabic: كرة الكواكب الثابتة [PH Morelon: I.5:3, 21:17]