 These were the most often-used 'clefs', or "litterae clavis" (key-letters), in Gregorian chant notation.Over time the shapes of these letters became stylised, leading to their current versions.Many other clefs were used, particularly in the early period of chant notation, including most of the notes from the low "Γ" ("gamma", the note written today on the bottom line of the bass clef) up to the G above middle C, written with a small letter "g", and including two forms of lowercase "b" (for the note just below middle C)