Basic Information on oldflux

	In August 1994, the nominal flux density of the ATCA's primary flux
	calibrator, 1934-638, was revised to give better agreement between
	the ATCA's flux density scale and the flux scales used in the northern
	hemisphere (the VLA in particular). For more discussion, see John
	Reynold's memo ``A revised flux scale for the AT Compact Array''.

	This introduces a problem when mixing data (either combining or
	just comparing) calibrated before and after this change. By default
	Miriad tasks use the new flux scale. However if you use the option
	`oldflux' in GPCAL and MFCAL when calibrating 1934-638, the old
	flux scale will be used. In this way, new data can be calibrated
	to have the old flux scale, and so can be combined/compared
	directly with data calibrated before the revision.
        
        In May 2016 the mm flux scale for 1934-638, which had been in use
        since 2009, was changed. The oldflux keyword can be used in a 
        similar fashion as above to switch between the old and the new
        flux model for frequencies above 11 GHz. The above discussion is
        for frequencies below 11 GHz.