[quote=@Zarkun]
<Snipped quote by Marayla>

Serial Number: I was told it was a five character thing.

Influence Mind: I...couldn't honestly say as I haven't read any of the novels and you never see it in game. If they do, I could argue Zack's is stronger than normal or something.
[/quote]

In the novels I've read, it seems to be all ghosts that have it.
In regard to serial numbers, there's
Agent X81505M,
Delta Emblock a.k.a Agent X10128B,
November Annabella "Nova" Terra, a.k.a. Agent X41822N,
Kath Toom a.k.a. Agent X52735N
etc.
My point is, they seem to all start with 'X,' have another letter at the end, and have numbers in-between.  They also all seem to be 7 digits.