This attribute specifies the DNIC (Data Network ID Code) of the
Cug by which packet networks are identified if the Cug is an
International Cug - it is specified as 4 BCD digits. This attribute is
not applicable if the Cug is a National Cug, as specified by the Cug
TYPE attribute. There are usually 1 or 2 DNICs assigned per
country, for public networks. The U.S. is an exception where each
BOC has a DNIC. Also, a group of private networks can have its
own DNIC.
DNIC value is not an arbitrary number. It is assigned by
international aggreement and controlled by CCITT.