inetnum:       [mandatory]  [single]     [primary/look-up key]
netname:       [mandatory]  [single]     [lookup key]
descr:         [mandatory]  [multiple]   [ ]
country:       [mandatory]  [multiple]   [ ]
admin-c:       [mandatory]  [multiple]   [inverse key]
tech-c:        [mandatory]  [multiple]   [inverse key]
rev-srv:       [optional]   [multiple]   [inverse key]
status:        [mandatory]  [single]     [ ]
remarks:       [optional]   [multiple]   [ ]
notify:        [optional]   [multiple]   [inverse key]
mnt-by:        [mandatory]  [multiple]   [inverse key]
mnt-lower:     [optional]   [multiple]   [inverse key]
mnt-routes:    [optional]   [multiple]   [inverse key]
mnt-irt:       [optional]   [multiple]   [inverse key]
changed:       [mandatory]  [multiple]   [ ]
source:        [mandatory]  [single]     [ ]