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.

مركزه مركزه‘concentric’

Arabic

References: PH Morelon: I.11:7, 39:19
Translation of:
Greek: περὶ τὸ αὐτὸ κέντρον [PH Heiberg: I.3:3, 74:13; I.11:7, 92:12-13]
Modern translations:
French: de même centre [PH Morelon: I.11:7, 38:28-29]
German: dessen Mittelpunkt sein Mittelpunkt ist [PH Nix: I.11:7, 93:12-13]
Synonyms:
(دائرة) يكون مركزها مركز هذا الفلك[PH Morelon: I.3:2, 19:6-7]
مخطوط على مركزه[PH Morelon: I.3:3, 19:10]