This object along with xcmPrtInterpPCLPtSizeNumerator sets the
default for the PCL-specific PJL variable 'PTSIZE'.
The PTSIZE variable only applies when the FONTNUMBER setting
specifies a scalable proportionally-spaced font.
The value zero shall mean not specified.
It is expected that a typical application will set this object
to the value 4. For example, if the denominator is set to 4,
describe a PtSize of 8.5, xcmPrtInterpPCLPtSizeNominator must
be set to 34.