schema:    TINC-KEY-SCHEMA
ref:       dn42.tinc-key
key:       tinc-key      required  single    primary  schema
key:       tinc-host     required  single
key:       tinc-file     required  single
key:       descr         optional  single
key:       remarks       optional  multiple
key:       compression   optional  single
key:       subnet        optional  multiple
key:       tinc-address  optional  single
key:       port          optional  single
key:       admin-c       optional  multiple  lookup=dn42.person,dn42.role
key:       tech-c        optional  multiple  lookup=dn42.person,dn42.role
key:       mnt-by        required  multiple  lookup=dn42.mntner
mnt-by:    XUU-MNT
mnt-by:    HEXA-MNT