Just a short quick question, relation to text of 1.1.3 in 2396bis about URL ref? (re-posted; 2nd attempt)

Just a short quickie question; no reply is ever expected or required.  
(Re-posted incase first message attempt was filtered out)
The text below is from one of my books on how to use/programme for BCB 
c++ (Borland Builder) published in 1998 which states:
"The URL is a subset of the Uniform Resource Identifier (URI) defined in 
the HTTP standard, RFC1945 (http://ietf.org/rfc/rfc1945.txt?number=1945). 
Web server applications frequently produce content from sources where the 
final result does not reside in a particular location, but is created as 
necessary. URIs can describe resources that are not location specific."
The above leads me to a belief that URIs are 'acting' as group attached 
to something that may or may not include a URL, while below (and from 
use) I know that several URI's with authority can be applied as a single 
URI with or without URL to yield resources of various types from server 
methods, blah, etc - However I am having minor complexes by wondering why 
the text in the current URI draft seems to me to be so different to the 
above understanding I have gained; In that there seems to be more than 
one URI within a URIs, eg:
http://www.ietf.org/internet-drafts/draft-fielding-uri-rfc2396bis-06.txt
1.1.3  URI, URL, and URN

  A URI can be further classified as a locator, a name, or both.  The
  term "Uniform Resource Locator" (URL) refers to the subset of URIs
  that, in addition to identifying a resource, provide a means of
  locating the resource by describing its primary access mechanism
  (e.g., its network "location").  The term "Uniform Resource Name"
  (URN) has been used historically to refer to both URIs under the
  "urn" scheme [RFC2141], which are required to remain globally unique
  and persistent even when the resource ceases to exist or becomes
  unavailable, and to any other URI with the properties of a name.

In a nutshell as I am - I was wondering – that perhaps the URL
references used in the draft text could be stated; like an RFC number
as the "Informative References" seem to have multiple choices which may
not be a bad thing but it is somewhat confusing considering the
reference to REC2141 for URN (or should I use that?).

In relation to my "URI vs Relative URI" post/s:
I did not actually think that the wording could be changed so easily but 
considering the new ideal expressed in posts by other list members I can 
now make a better understanding of what is being expressed. Ie: 
Relative-REF vs Relative-URI. Now the 'gargiols' can be stone lions, or 
even lions if one wishes, etc (perhaps its the air or at night they may 
look like real lions – lol – In any case I would hope to see them one day 
for myself in person – another story).. 
All in all its very well constructed – full credit to you all for your 
work.
:)