[jurialmunkey]

Just make sure that you wrap the entire expression in square brackets.
e.g.

Code:


<expression name="exp1">[Cond1 | Cond2]</expression>
<expression name="exp2">[Cond3 + Cond4]</expression>
<expression name="exp3">!$EXP[exp1] + $EXP[exp2]</expression>


Because that will make sure that exp3 equals
![Cond1 | Cond2] + [Cond3 + Cond4]

But if you hadn't wrapped in the square brackets then you would get a very different overall condition:
!Cond1 | Cond2 + Cond3 + Cond4