CondExpr...

is an expression parser. You use it via the "expr" markup, thusly:

   (:if expr equal {$var1} {$var2} xor equal {$var3} {$var4}) 

   (:if expr ! equal 'carrot' {$var4}) 

Operations available are:

• and
• or
• xor
• &&
• ||
• !

I think you can also use parenthetical expressions like

(: if expr ({$bool1} or {$bool2}) and ({$bool3} or {$bool4}) :)

Usage examples here: Cookbook:JJSApprovePage