Hierarchical Routing Designators.


   A system that supports hierarchical routing will identifies
   itself with the "H" feature letter in it's SID.

   A hierarchical routing designator is composed of any number
   of fields delimited by dot ("."). The fields are in the order
   more to less specific location, from left to right (see examples below).

   A hierarchical routing designator may contain up to 31 charactors
   beyond the initial (six character maximum) traditional designator,
   including the dot delimiters. There is no explicit limit on the number
   of fields. Each field may contain at most six characters, not including
   the dot delimiters.

   Examples:

   w0rli.norcal.usa
   ja2xxx.32.j2net.jpn.asia
   amsat
   md.usa
   95060.ca.usa


   How does compatiblity with existing systems work?


   When a system that handles hierarchical designators receives
   a message from a system that does not handle them there is no
   problem. Things work as they always have.

   When a system that handles hierarchical designators sends
   a message to a system that does not handle them, it sends
   the leftmost field of the designator as the "@ BBS" field.


   How does forwarding work?

   For each message, each field of the hierarchical designator becomes
   a candidate key for routing the message. They leftmost field of
   the hierarchical designator that matches an entry in any routing
   list is used to forward the message. For example:

   ja2xxx.32.j2net.jpn.asia

   If ja2xxx is in my route list, I route to him directly.
   If 32 is in my route list, I use that route.
   If j2net is in my route list, then I use it.
   If jpn is in my route list, then I use it.
   If asia is in my route list, then I use it.

   Stations outside asia would all have asia in their route list,
   routing their traffic to some nearby HF gateway which can route
   to asia. The HF station that routes to Japan would route using
   the jpn part of the designator. Inside Japan, the gateway station
   would route toward the JA2 districts using the j2net part of
   the designator. Inside JA2, stations would route toward the
   correct region using the 32 part of the designator. Inside
   the 32 region, stations would route directly to ja2xxx using
   the first part of the designator.


   One useful way to think about hierarchical designators is to
   think of the "." as meaning "is within" . Thus the designator
   w0rli.norcal.usa means "w0rli, who is in norcal, which is in usa".



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