Neat. Though the name is a misnomer. It uses Unicode, and not the ASCII subset, to handle characters like ┼ (Box Drawings Light Vertical and Horizontal) and ╰ (Box Drawings Light Arc Up And Right). The latter wasn't even part of cp437.
The latter is taken by several other text-based plotting packages of a similar nature, so I would suggest the former name.
FWIW, many plotting toolkits have an ASCII backend, like "set terminal dumb" in gnuplot. My suggestion therefore is to not make this a general purpose plotting package. ;)