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.

with the same center‘concentric’

English

References: PH Hamm: I.3:3, 46:21
Translation of:
Greek: περὶ τὸ αὐτὸ κέντρον [PH Heiberg: I.3:3, 74:13; I.11:7, 92:12-13]
Synonyms:
around the same center[PH Hamm: I.11:7, 56:22]
concentric[PH Hamm: I.3:2, 46:18]