There isn't a coding limitation, it's just limited by guild choice really (and some coding to stop non-guild skills from giving xp).
I don't imagine it would be difficult to work around that though. The reason is though that the way the guilds WERE set up is that they almost naturally fell into those 3 categories.
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If you say plz because it is shorter than please, then I will say no because it is shorter then yes.
