Csleutel

Csleutel is a term used in Dutch-language discussions of musical notation to refer to the C-clef, a family of clefs that designate middle C on a specific line of the staff. The standard Dutch spelling is usually C-sleutel, but Csleutel appears in some texts without a hyphen or as a historical spelling variant.

Five variants exist, corresponding to the line on which middle C is placed: soprano C-clef on the first (bottom) line, mezzo-soprano C-clef on the second line, alto C-clef on the third line, tenor C-clef on the fourth line, and baritone C-clef on the fifth (top) line. In each case, the line marked C represents middle C, and the notation around it is written accordingly. These clefs were primarily used in vocal and choral music as well as some forms of instrumental music in medieval and Renaissance periods, when the standard treble (G) and bass (F) clefs did not always fit the range of the part.

Over time, the C-clefs fell out of general use in favor of more standardized clefs, and by the 18th century they were largely confined to scholarly editions of early music and specialized scores. Today, Csleutel is mainly of historical interest, referenced in discussions of notation practices or in translations of older music manuscripts. In modern contexts, writers typically refer to the clef as C-clef or specify which line serves as middle C.