Where is the edge of the Internet?

> 1 - Connection Taxonomy
> 1.1. The Internet is a "network of networks", where the component
> networks are called Autonomous Systems (AS), each having a unique AS
> Number (ASN).

Even if this reflects the original intent of ASNs, it certainly does not fit
current reality.

it is (a) accurate to the original definition, and (b) relevant to finding
the "edge". everything else you added:

Let's call any set of networks under a unified administrative control
an Autonomous Routing Domain (ARD). ARDs should not be confused with
ASes (an implementation detail). They are distinct for these reasons:

1) Most ARDs do not have an ASN -- they are statically routed "at the edge".
2) Many networks "at the edge" use private ASNs.
3) Many ARDs share a provider provided ASN -- RFC 2270.
4) Many ARDs are implemented with multiple ASNs. Internap is probably
   an extreme example. But even UUNet's global ARD (AS701, 702, 705 ...)
   reflects an implementation choice (one that Sprint does not seem to
   follow with 1239, for example).

...is also completely true, and points to a possible need to upgrade the
terminology in general use. however, for the purpose of finding the edge,
the original (and still officially current) definition of "ASN" will serve.