op - set options					RWW & MWP

op ap:			This controls automatic plotting of spectra with
			'pl' after commands like 'rt' and 'li.' If auto plot 
			is on, this turns it off, or if it was off it is 
			turned on.  
op no (yes)		Turn off (on) auto plot.

op ucl:			Switch between mixed case labels on plots and upper
			case only.

op sp:"/ua/xyz"		Set the default stacks path to /ua/xyz.

op rc:			Select maps in current relative coordinates.  See
			documentation of 'cm' for discussion of mapping of the
			sky onto the page.
op ortho:		Choose maps with Orthographic projection.
op merc:		Choose maps with Mercator projection.
op gnom:		Choose maps with Gnomic projection.
op po:			Choose maps with polar projection.

op yw:			Toggle to supply an automatic yes answer to warning 

op msg:1		Turn off messages generated when a BLANK value is 
			encountered in a stack.

op dp:			This is a toggle used to suppress ALL plotting, e.g.
			pl, cm, lk. It can be used with "ro" to capture the 
			numeric output of commands without capturing the
			plotting code (e.g. the Tektronix code used for xterms).

Op is a way to control general options in comb. 

Op ap: is a toggle to automatically plot a spectrum after most operations
(e.g.  'gt', 'rt', 'li', 'is').

The string given to 'op sp:' is the path to be pre-pended to the stacks
directory named with 'ns' (comb adds the final slash if needed). The default
path is the value of the environment variable LSTACKS or an empty string if
LSTACKS is not defined.

The flags 'rc:', 'ortho:', 'merc:', 'gnom:', and 'po:' indicate the projection
to be used by map-making routines ('cm', 'vc', 'wc').

Op yw: is a toggle to automatically answer yes to warning messages which ask
"Do you want to continue?". This option should be used with caution!

Op msg: controls the verboseness level of the message comb gives you when it
encounters a stack (but not an image) with a BLANK value (aka DRAGON, .DR, 
IEEE NaN, or FITS BLANK) in it. The levels are

0 -- "Don't ask, don't tell." This instructs comb to not even check for
     BLANKs in stacks. Use this if you know you don't have any BLANKs 
     and aren't likely to generate any yourself.
1 -- Check for BLANKs when a stack is brought into stack 1, 2 or 3, but
     issue no message.
2 -- Generate a message when a stack with a BLANK is brought into
     stack 1, 2 or 3. 

The default message level is 2. Comb automatically replaces the BLANK(s) by
calling 'el' on the offending channel(s). Only the copy of the spectrum in
stack 1, 2 , or 3 is affected; the disk stack (stacks 4 and higher) remains
unchanged. Therefore commands which interpolate over a large enough area can
generate multiple messages for the same stack. To avoid repetitive checking,
only routines which might put something in stacks 1, 2, or 3 actually check for
BLANKs. These commands are ad, af, co (if ad: or su: are not 1 or 2) , cm, gt,
is, lk (if chk: is given), rt, st (into 1, 2 , or 3 ), th, vc, vm, wc, and xf.  
The other commands don't check, under the assumption that whatever put data
into stack 1, 2, or 3 has already checked.  So if you are pathological enough
to do something like

-> rt 10; c .stak(32)=.DR; li 1

you'll get nasty behavior, and you'll have no one to blame but yourself.

In general, scans made by Bell Labs and NRAO won't have BLANKs, but scans
from FCRAO sometimes do.

This document was last updated on Tue Oct 17 16:24:05 EDT 2000 by Marc W. Pound.