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.

length of the hour in time degrees ‘length of the hour in time degrees’

English

References: Alm. Toomer: 104
Translation of:
Greek: ὡριαίοι χρόνοι [Alm. Heiberg: II.9, 144:9]