group_data(?Field, 
?GroupData, ?Value)Value is the value for Field GroupData. 
Defined fields are:
- name
 - Name of the user
 
- password
 - Password hash of the user (or 
x if this is not accessible) 
- gid
 - Numeric group id of the group
 
- members
 - List of user-names that are member of this group.