[ic] How to use Variable in perl?

[Interchange User]

(sorry for the previous mail... accidentally pressed "send"  :P  )

I have a Variable definition in catalog.cfg, like this:
Variable        GOLD    Gold

To use this variable in a html page, it's simply:
Gold = __GOLD__

right?  But how can I use it in a perl block?  Eg, a snippet:

[perl arg="values scratch"]
  $b = "";
  $b .= "membership_type=";
  $b .= "__GOLD__";
  $Scratch->{b} = $b;
  return;
[/perl]
[scratch b];


Of course, the above perl block does not work.  What could be wrong?  
I think this should be very simple, but I just couldn't figure that 
out.