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.

ὀρθογώνιον‘lit. rectangle, it denotes multiplication between two line segments’

Greek. – Grammar: adj used as noun.

References: Alm. Heiberg: I.10, 33:6
Translated into:
Arabic: سطح / السطح القائم الزوايا  [Alm. MS Tunis: ]
Arabic: سطح [Alm. MS Leiden: f. 6r]
Modern translations:
English: lit. rectangle, it denotes multiplication between two line segments