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.

الحصّة الوسطي ‘average increment’

Arabic

References: Alm. MS Tunis:
Translation of:
Greek: μέση ἐπιβολή [Alm. Heiberg: I.10, 47:10]
Synonyms:
الحصّة الواسطة[Alm. MS Leiden: f. 8r]