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.

Aḥmad ibn al-Sarī Ibn al-Ṣalāḥ, Qawl fī Bayān mā wahama fī-hi Abū Naṣr al-Fārābī

Mashhad, Āstān-i Quds, 5593 · p. 88

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