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.

سطح ‘plane’

Arabic

References: PH Morelon: I.9:1, 29:2; I.11:1, 37:17
Translation of:
Greek: ἐπίπεδον [PH Heiberg: I.9:1, 80:29; I.11:1, 90:10; I.12:1, 94:9]
Modern translations:
French: plan [PH Morelon: I.11:1, 36:22]
German: Ebene [PH Nix: I.11:1, 91:12]
Synonyms:
بسيط[PH Morelon: I.12:1, 43:3]
بسيط [Alm. MS Tunis: ]
مسطوح[Alm. MS Tunis: ]