"Enter Unlock Code"

Hey all, I'm new here.
So I've bought the game and when I customize my character, there's this option that says 'enter unlock code'. What's that about? Where do I find such a code and what does it do?

Thanks in advance

[RealSubZero]

at the enter unlock code screen you write phayder to unlock Alanna (Necris) and jihan to unlock Ariel (Iron Guard)

[Giggity]

Don't they come when you type "unlockallchars"?

[EhWol]

Is this PS3 PC or both?