Trigger using environment variable

Does anyone know if it is possible to get a trigger to use some king of environment variable instead of hard-coded text? Basically I would like to have the same trigger installed on 2 ISs. The triggers would filter the document based on a field called target. If the field is “IS01” then the trigger on IS01 should kick of its service but if the value is “IS02” then IS02 should kick off its service.

Of course I could hard-code the values “IS01” and “IS02” into each of the triggers but I was wondering if there was a way of doing it dynamically. So that if I set up a new IS called IS03 I would only have to install the trigger and set an environment variable to IS03.