# All letter keys are subject to optimization. Punctuation and digits remain stationary.
# ~ 1 2 3 4 5 6 7 8 9 0 - =
mask = 0 0 0 0 0 0 0 0 0 0 0 0 0
# q w e r t y u i o p [ ] \
mask = 1 1 1 1 1 1 1 1 1 1 0 0 0
# a s d f g h j k l ; '
mask = 1 1 1 1 1 1 1 1 1 0 0
# z x c v b n m , . /
mask = 1 1 1 1 1 1 1 0 0 0