I can't seem to find anything about it when I search the forums. I'm making small changes in the script file for a mod, and was wondering what the number following any variable name stands for.

The number actually is part of the variable :) Variables ending with 0 tend to indicate the actual unit of the event (or the actual city, your civilization, etc.). Variables ending with 1 indicate enemy civilizations, units from another civ. So always 0 is for the "ours" and 1 is for the "theirs"). It is not a general rule, its merely empiric evidence. Normally, you don't want to modify the numbering because then you would modify the subjects of a sentence (for example you play as the Maya and the Russians greet you and name themselves as Mayans - quite funny, isn't it? :) ). I am also unsure of what would be the value of other variables, maybe they are uninitialized or hold obsolete values. Based on the game's general fault tolerance - well, the lack of it - I can imagine it could even crash if you reference an unexisting variable. I hope I shed some light on the matter.

To be clear: do not modify the names. They are specific patterns that the game looks for to replace with variables, which only have a meaning in certain contexts. But you can remove or move them around if you want. :)

To be clear: do not modify the names.:)

Do you think my comment was enigmatic? :D

Hmm, right now the only thing that I wanted to change was #ESPIONAGE_MISSION_INITIATE_PROPAGANDA_IMMUNE
#caption Espionage in $CITY0
The $CIVADJ1 people are immune to propaganda.
into something like
#ESPIONAGE_MISSION_INITIATE_PROPAGANDA_IMMUNE
#caption Espionage in $CITY0
$RULER_TITLE0, a propaganda campaign against the $CIVNOUN1 won't succeed because the $CIVADJ1 people are so [pious] and [moralic].
So the only thing I can do is to just test run the game to see if it works?

I would advise, when changing text, to keep the exact same parameters.

Something like

#ESPIONAGE_MISSION_INITIATE_PROPAGANDA_IMMUNE
#caption Espionage in $CITY0
$A propaganda campaign against $CITY0 won't succeed because the $CIVADJ1 people are so [pious] and [moralic].

should work

I think you probably mean to say moralistic, not moralic, which isn't a word in english.

I would advise, when changing text, to keep the exact same parameters.

Something like

#ESPIONAGE_MISSION_INITIATE_PROPAGANDA_IMMUNE
#caption Espionage in $CITY0
$A propaganda campaign against $CITY0 won't succeed because the $CIVADJ1 people are so [pious] and [moralic].

should work
Aha, you came up with a good way to phrase it. Thanks!

I think you probably mean to say moralistic, not moralic, which isn't a word in english.
Oh OK, thanks!