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.

وتر ‘chord’

Arabic

References: Alm. MS Tunis:
Translation of:
Greek: ἡ ὑπό (περιφέρειαν) εὐθεῖα [Alm. Heiberg: I.10, 42]
Synonyms:
الخطّ المستقيم الذي يوتر قوس اب [Plan. Sidoli+Berggren: 109(2), 117, 119, 135, 137, 148, 150, 159, 160]