I have a code like..

Input
!a

Output
message store1
message store2
message store3


How do I make it so that I can make it so I can "activate" certain parts of the code so it'll be something like this..

Input
!a

Output
message store1
message store2
message store3

And if I don't have message 3 to be displayed, I can do...

Input
"some activation code"
!a

Output
message store1
message store2

I know I can change the variable to something like !b and have it output store1 and store2, but I would like to be able to choose which messages to be displayed from the !a variable only. Is this sort of thing possible? Thanks..

Your examples are not clear enough to understand what you actually want. Try some REAL examples, pls.

!loc
store1
store2
store3

!store1 inactive

!loc
store2
store3

1. On "!inactive storeX" set %storeX $null and on "!loc" check each %storeX for being empty.
2. Make %checkStoreX for each %storeX and store in %checkStoreX on\off (1\0) for "!active\!inactive".