Tonic sol-fa is a peagogical technique for teaching sight-singing, invented by John Curwen. It uses a system of musical notation based on movable do solfege, whereby every tone is given a name according to its relationship with other tones in the key: the usual staff notation is replaced with anglicized solfege syllables (e.g. do, reh, me, fa, so, la, te, do) or their abbreviations (d,r,m,f,s,l,t,d). "Do" is chosen to be the tonic of whatever key is being used (thus the terminology moveable Do). The original Solfege sequence started with "Ut" which later became "Do".