Registers can be used anywhere where integers can. Registers are assigned using the 'L'et command, or the Set Channel Register command.
R0-R9 are local channel registers, these are private for each moan channel.
RA-RZ are shared moan registers, these are global across all the moan channels.
Registers X,Y and I are also local to each channel. X and Y hold the x and y position of the first sprite/viewport that was attached to the channel. I holds the image index of the first sprite attached to the channel. If the first object to be attached was a viewport, then I is always -1.See also the Set Channel Register and Channel Register commands.