you're not talking about a "Hide" condition, you're talking about an "Include" condition.
If you want to be able to hide, and unhide it, you need to use a hide condition.
If you want to exclude it from the form completely then use an "Include condition".
If you want to hand-code the equivalent of either then I recommend putting something into the template setting, like say XAXA, and then doing a right-click, "source" on the procedure, then search for XAXA to see how it is used.
cheers
Bruce