A Quick Question - (add stage ?)

So i've been scripting missions for a week now (learning) and was wondering how relevant the numbers are in the "add stage" line, i know the last stage has to be "final", but does it matter if it's 0, 1 or 3 etc for the previous stages. Looking through the game files they seem pretty random. Are they certain numbers for certain objectives ?

Those numbers are mostly pointless