Archaic forms of musical notation used in the Medieval era and the Renaissance. Any form of musical notation using symbols or letters rather than notes on the staff to describe pitches.For guitars and other plucked instruments it is possible to notate tablature in place of ordinary notes. In this case, a TAB-sign is often written instead of a clef. The number of lines of the staff is not necessarily five: one line is used for each string of the instrument (so, for standard 6-stringed guitars, six lines would be used). Numbers on the lines show on which fret the string should be played. This Tab-sign, like the Percussion clef, is not a clef in the true sense, but rather a symbol employed instead of a clef. The interstitial spaces on a tablature are never used.