Unit guild information?

[myslex]

Hello everyone,

I am writing an addon that in theory should make it easier to spot guild members in the world by showing an icon close to the reticle when you hover (reticleover) over a person that is in any of the guilds that you are a member of.

HOWEVER, I cannot find any api functions that return guild information for a unit like GetNumGuilds() for reticleover ie:

local num = GetNumGuilds('reticleover')

Is it not possible?
Any help greatly appreciated.

MYxLEs