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.

its complement ‘the complement of (the arc)’

English

References: Alm. Toomer: 73
Translation of:
Greek: ἡ λοιπὴ εἰς τὸ τεταρτημόριον [Alm. Heiberg: II.2, 91:12]