	CB is similar to C1 and C2.  It averages together the data for 
	subscan numbers .01 and .03 (for filter bank data) or
	.11 and .12 for hybrid spectrometer data.

	Any non-integer fraction of the scan numbers is ignored.  There
	is no check for duplicate scan numbers.

	The type of data (filter bank or hybrid spectrometer) is
	set by FBDATA or HCDATA respectively.

	File name: cb.prc

	This procedure is include in LSETUP.12meter
