role:          [mandatory]  [single]     [lookup key]
address:       [mandatory]  [multiple]   [ ]
country:       [mandatory]  [single]     [ ]
phone:         [mandatory]  [multiple]   [ ]
fax-no:        [optional]   [multiple]   [ ]
e-mail:        [mandatory]  [multiple]   [lookup key]
trouble:       [optional]   [multiple]   [ ]
admin-c:       [mandatory]  [multiple]   [inverse key]
tech-c:        [mandatory]  [multiple]   [inverse key]
nic-hdl:       [mandatory]  [single]     [primary/look-up key]
remarks:       [optional]   [multiple]   [ ]
notify:        [optional]   [multiple]   [inverse key]
mnt-by:        [mandatory]  [multiple]   [inverse key]
changed:       [mandatory]  [multiple]   [ ]
source:        [mandatory]  [single]     [ ]