02-03-2016, 08:57 PM
I should probably add that I've assumed for a while now that <sh> was taken from the abbreviation for "circ" because of its shape, not for its sound value. It seems that whoever devised the script wanted a glyph that resembled <ee> in some way, because this glyph can often occur in the same position of a word as <ee> does (i.e. substitute for it).