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.

ihr Verhalten, wenn sie zu irgend einer Ebene in Beziehung treten ‘spatial ratios’

German

References: PH Nix: I.2:1, 73:14-15
Translation of:
Arabic: حالها إذا قيست بسطح من السطوح [PH Morelon: I.2:1, 17:10-11]