The following are the types of keys used to switch modes on Casio cash registers.
OP (Operator) key
Used to access the most basic modes of operation only.
M (Master) key
Used to access some modes of operation.
OW (Owner) key
Used to access most modes of operation.
In some Casio cash registers, it has the same function of as the PGM (Program) key.
PGM (Program) key
Used to access all modes of operation, including the Program mode.
