[TDO2000]

So the third use of my description:
variables:
there are 2 types of variables
1. the global (for every NPC in the room)
2. this. variables for only one NPC

variables are used for numbers and stuff like this...
example

if(playertouchsme){
a=1+3;
message #v(a);
}

if u touch him he will say 4 =)

so this variables:

if u have an NPC which uses normal variables (without this) it is set for all npcs in the level
example:
1. NPC:
if(playertouchsme){
a=1+3;
message #v(a);
}

2. NPC
if(playertouchsother){
message #v(a);
}

so if u touch the 1. NPC both will say 4

if u use this.variables
example:
1. NPC:
if(playertouchsme){
this.a=1+3;
message #v(a);
}

2. NPC
if(playertouchsother){
message #v(this.a);
}

then if u touch the first NPC it will say 4 but the second will say 0 (it's what every variable is before u set it)

hope u'll understand and Loriel it's always good to use things no new scripter will understand to explain how something like this.-variables work...