X-no-Archive:yes
With Jeff's permission, here is his lucid answer to this wondrous question,
and a guide for the perplexed.

Greg Stigers
http://www.cgiusa.com

-----Original Message-----
From: VANCE,JEFF (HP-Cupertino,ex1) [mailto:[log in to unmask]]
Sent: Tuesday, August 15, 2000 5:31 PM
To: Stigers, Greg [And]
Subject: RE: Command file wonders

Hello Greg,

You can post this to 3000-L if you wish.

...
> Why does this happen?  Why doesn't the variable x increment to 4?
>
> MPEiX:PRINT TEST
>1)   parm x
>2)   setvar x !x + 1
>3)   echo !x
>4)   setvar x !x + 1
>5)   echo !x
>
> MPEiX:test 2
> 2
> 2
>
> MPEiX:showvar x
> X = 3

All parms in UDCs and command files must be referenced explicitly
via !parm_name. Variables can be referenced explicitly or implicitly
(name only -- no "!").  However implicit referencing is only permitted
in the following CI commands: CALC, ELSEIF, IF, SETVAR, WHILE and
![expression] constructs.  Last, parm value cannot be changed within
the UDC/script, that is, they are like Pascal 'readonly' arguments.

Analyzing the above script:
  line 1 defines a parm named X
  line 2 creates a CI variable named X to the value of the parm X plus one
         (3, in this example)
  line 3 echo's the value of the parm X (2)
  line 4 modifies the CI variable X to the value of the parm X + 1. (3)
  line 5 echo's the value of the parm X (2)

The SHOWVAR X displays the value of the variable X.

The following script will create a variable of the same name as a parm
(why you would want to do this I have no idea!) and displays the value
of the parm and of the variable:

  parm y=2
  setvar y !y+1
  echo parm=!y    # see 2
  echo var=![y]   # see 3
  calc y          # see 3
  calc !y         # see 2
  setvar y y+1
  showvar y       # see 4
  echo !y         # see 2
  setvar y !y+1
  showvar y       # see 3

More info is on Jazz at:
http://jazz.external.hp.com/papers/SolSymposium_00/CIprogramming/index.htm


Hope this helps,
 Jeff Vance, CSY