IVAL.i4.v = MAXTOL( INDATA.i1.r, IERR.i2.r [, UNITS.i4.r] )

	Scaling service routine: Obtaining The Unprocessed Tolerance.
	IVAL    unprocessed tolerance/maximum data from the Alarm Block.
		For ANALBL property, the value is suitable for processing
		by PDUDPU or PDUDCU.  For DGALBL property, the value is
		a bit pattern mask of defined bits.

	INDATA  unprocessed analog or digital Alarm Block as returned by
		a DPGET.  

	IERR    error code returned as 0 for success.  

	UNITS   Optional argument in which the units text is returned as 4
		ASCII characters in a longword integer field.  
		(use with FORTRAN CHARACTER*4 via %REF(char)).
		The text is one of "MAX ", "TOL ", "%TOL", "MASK" or
		"    " for MAXimum value, TOLerance, percent TOLerance,
		digital MASK or undefined.