SYNTAX            : ARG U REG

RESULTING ARGUMENT: None

FUNCTION          : Set the value of the register whose name immediately
                    follows the command to the value passed as argument.

ARGUMENT          : The new value for the register.

EXAMPLE           : . U 1
                    Load register 1 with the current position of the cursor
                    in the buffer.

NOTE 1            : If the register contains a string-value, then that
                    string is lost. From then on, the register is treated
                    as numeric.

7.0:
NOTE 2            : To access the register as an array, a subscript can be
                    used.

MATRIX