Letters in array position?

I’m trying to fix this badly coded map app, and I notice that about 4 times through out, who ever coded it used letters in addition to numbers in an arrays position.

risksArray["r"+element.@riskCode] = whatever;

but throughout the whole thing, he always refers to the array positions the same way… so I can’t figure out why he would possibly just add an r to the beginning like that.

How does that work? Why would someone do it?

thanks… I’m currently changing them all back to just numerical.