When machining is actually started, it is necessary to rotate the spindle,
and feed coolant. For this purpose, on–off operations of spindle motor and
coolant valve should be controlled.
The function of specifying the on–off operations of the components of the
machine is called the miscellaneous function. In general, the function is
specified by an M code (See II–12).
For example, when M03 is specified, the spindle is rotated clockwise at
the specified spindle speed.