Currently under development.
After successfully loading MODE, the instructions H, I, Q, and S
take on new semantics, which alter four new states or 'modes' of the
current IP.
H toggles an internal flag called hovermode on and off. In hovermode,
the instructions >, <, ^, v, |, and _ treat the IP's delta
relatively - instead of setting the dx to 0 and dy to -1, ^ would
instead simply subtract 1 from dy.
The I "Toggle Invertmode" instruction toggles an internal flag called
invertmode. When invertmode is active, cells are pushed on the
stack onto the bottom instead of the top.
The Q "Toggle Queuemode" instruction toggles an internal flag called
queuemode. When queuemode is active, cells are popped off the
stack from the bottom instead of the top.
S toggles switchmode on and off. In switchmode, the pairs of
instructions [ and ], { and }, and ( and ) are treated as
switches. When one is executed, the cell it is located in is immediately
overwritten with the other instruction of the pair, providing a
switching mechanism and a way to seperate coincident IP's.