YAXIS

     YAXIS contains the lower bound, upper bound, label increment, and 
     frequency information separated by slashes in the form:

		lower/upper/increment/lbfq;gdfq;tkfq

     The frequencies for labels, grid lines, and tick marks follow the 
     last slash and are separated with semicolons.  If the increment is 
     positive, all the label values will be divisible by the increment.  
     If it is negative, the label values will begin with the lower value 
     and be separated by the increment.  The bounds and increment are for 
     the scaled data.

     Defaults will be supplied if no specification is given.  The following 
     defaults will be used when appropriate:

	vcoord	lower	upper	defaults
	------	-----	-----	----------------
	PRES	1020	100	Mandatory levels
	THTA	270	400	10
	HGHT	0	20000	1000