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.

κέντρον ‘centre’

Greek. – Grammar: n.