the usage of group?

[Rubby]

Hi,all,
I use freeRadius + Oracle,
I noticed the sql scheme for oracle included some tables about group.
here are table radgroupcheck ,radgroupreply:
CREATE TABLE radgroupcheck (
        id              INT PRIMARY KEY,
        groupname       VARCHAR(20) UNIQUE NOT NULL,
        attribute       VARCHAR(40),
        value           VARCHAR(40)
);
CREATE SEQUENCE radgroupcheck_seq START WITH 1 INCREMENT BY 1;

CREATE TABLE radgroupreply (
        id              INT PRIMARY KEY,
        GroupName       VARCHAR(20) UNIQUE NOT NULL,
        Attribute       VARCHAR(40),
        Value           VARCHAR(40)
);
CREATE SEQUENCE radgroupreply_seq START WITH 1 INCREMENT BY 1;

here the groupname needs unique,
That means there is only one attribute that a group should check and reply,
what means that? 
If I need the group check and reply a few attributes, can I?
Who can tell me the usage of group here?
Any help is appreciate.





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