An enum is just a enumaration, which means it's assigning a string a number (Counting upwards from 0 as the word enumation implicates). In your exampel userid = 0, team = 1, class = 3 and so on. You don' need the enum. It just makes it easier to read the code.
The array is a way to store the informations (as you maybe know).
So to access a clients userid you could write
HTML Code:
userArray[client][userid]
or
HTML Code:
userArray[client][0]
that would be the same.