Hey Mike,

The code is a little bit verbose with a ZPL, but the concept is as follows:

• Determine all the loaded Glass Catalogs in the correct order that are for the current system
• Loop through all the new materials (NM) defined for the specific catalog
• Once the iterator hits the desired glass number, return the glass name and exit the loop

desired_glass_number = 27

! get all the loaded catalogs
dummy = SYPR(23)
catalogs$ = $BUFFER()
glasscat_dir$ = $DATAPATH() + "\Glasscat\"

! determine the number of loaded catalogs by counting the white spaces
! NOTE: there is always a space after a catalog, even if there is only 1 loaded
num_catalogs = 0
FOR i = 1, SLEN(catalogs$), 1
	tmp$ = $LEFTSTRING(catalogs$, i)
	tmp$ = $RIGHTSTRING(tmp$, 1)
	IF tmp$ $== " " THEN num_catalogs = num_catalogs + 1
NEXT

! loop through the catalogs in order and look for valid glass names
glass_num = 0
FOR i = 1, num_catalogs, 1
	catalog$ = $GETSTRING(catalogs$, i)
	catalog_file$ = glasscat_dir$ + catalog$ + ".AGF"

	! check to make sure the file exits
	filter$ = catalog_file$
	FINDFILE tmp$, filter$
	IF (SLEN(tmp$))
		OPEN catalog_file$
			LABEL BOF
			READSTRING line$
			IF (EOFF()) THEN GOTO EOF

			! check if the line is a new material
			! ideally we would trim the string to remove whitespaces
			marker$ = $LEFTSTRING(line$, 2)

			! ideally we would convert all letters to uppercase but we'll assume NM is uppercase
			IF (marker$ $== "NM")
				glass_num = glass_num + 1
				glass_name$ = $GETSTRING(line$, 2)

				! check the glass_num
				IF glass_num == desired_glass_number
					PRINT "Glass Number ", $STR(glass_num), " is for ", glass_name$, " material"

					! let's verify this is the true
					PRINT "VERIFY ", GNUM(glass_name$)

					GOTO EOF
				ENDIF


			ENDIF
			GOTO BOF
			LABEL EOF
		CLOSE
	ENDIF
NEXT

Thanks Michael, I’ll give this a try.

Of course, a ZPL string function $NUMGLASS(i) where “i” is the glass number in a catalog would do this in one line, if it existed.  But we all know that Zemax is 100% nonresponsive to any customer requests, so that will never happen.  I/we all wish that Zemax could be as responsive as you have been.  Thanks, Mike