Online Encyclopedia of Western Signs and Ideograms Symbols.com

Symbol 11:3

1103

11:3 · A cross sign called button cross in Christian symbolism.
    When this sign is turned 45 degrees it becomes a cross used in musical notation before the note sign, called a double cross. As such it is also drawn 0903, 5101, or 4525. It indicates that following note or notes should be played two half-tones higher than the note signs' positions show.
    See also 5101 in Group 51.