NX if statement on environmental Variable

Hello,

I created a .dat File to overwritte some environmental variables in NX,

Something like this:
UGII_TEMPLATE_DIR="destination on the server"

my question is if I don't have access to the server for some reason, how can I make NX ignore this variable and use the default ones?

Is there and if statement I can do?
I'm really new to this, don't really know what I'm doing :)

Thank in advance