pgAdminIII and User Grants

i'm trying to grant a user permissions in pgadminiii.
however, the only option it gives me is for the group
"public".

in addition, i can grant privileges at the db level,
the schema level, the public schema level, the generic
table level and the specific table level.

no choice allows a single user to have privileges
added and it isn't at all clear to me what levels i
need to grant privileges since i have 5 choices.

any advice w/b appreciated.

tia...



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