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<font size=3>Gabe wrote:<br>
</font><blockquote type=cite class=cite cite="">
<font face="Arial, Helvetica" size=2 color="#000080"> <br>
This is good stuff, Joaquin, but it seems to be at odds with the use of
term “identifier” in the URI/web context.<br>
<br>
Any string that conforms to the URI syntax (RFC 3986) is defined as a URI
(a type of identifier). There’s no need for that URI to refer to exactly
one entity. The URI exists simply by minting it (writing it down). Thus,
I don’t see how that aligns with the statement (summarizing your summary)
that an identifier is a name in a context that “refers” (what does
*<b>THAT</b>* mean) to a single entity. </font></blockquote><br>
Thanks, Gabe. I don't deny that it seems to be at odds. If
it i s at odds, then i am
wrong. <br><br>
I won't rise to the refers bait (though it sure is well placed!), but if
we can take that as understood, here is how
i see the situation:<br><br>
The namespace of URIs is defined by the URI syntax. Any string that
fits the syntax is a name in the URI namespace. [RFC 3986 :
3]<br><br>
"A Uniform Resource Identifier (URI) is a compact sequence of
characters that identifies an abstract or physical resource." [RFC
3986 : Abstract]<br><br>
I feel that sentence says a sequence of characters is not an URI unless
it identifies a resource.<br><br>
But let's read on, and give a sympathetic reading. <br><br>
I feel that Clause 3, when it says things like "Each URI begins with
a scheme name that refers ... ," means exactly that: each URI
conforms to the syntax. It does not mean that each sequence of
characters that conforms to the syntax is a URI. When Clause 1.1
says "A URI is an identifier consisting of a sequence of
characters matching the syntax rule named <URI> in Section 3,"
it means just that: every URI matches the rule, not every sequence of
characters matching the rule is a URI. <br><br>
But I feel it is the intention of the RFC that that each sequence of
characters that conforms to the syntax is a name in the URI
namespace. It's simply that every name in that namespace is not
necessarily a URI. I feel that fits with the X.900 definition:
"2-12.3 Name space: A set of terms
usable as names." <br><br>
Back at Clause 1.1, we find: "An identifier embodies the information
required to distinguish what is being identified from all other things
within its scope of identification. Our use of the terms 'identify'
and 'identifying' refer to this purpose of distinguishing one resource
from all other resources, regardless of how that purpose is accomplished
(e.g., by name, address, or context). ... Likewise, the
"one" resource identified might not be singular in nature
(e.g., a resource might be a named set or a mapping that varies over
time)."<br><br>
I feel that the X.900 definition works with this. That a name
refers to one entity at a certain time and at another at a different time
works with "2-12.2 Identifier: <a name="12.2"></a>An unambiguous
name, in a given naming context." Such a name is not
necessarily ambiguous. Example: 'President of the United
States'. Our system of laws, here in the middle of North America,
is based on that being an unambiguous name in the context of our system
of laws. We have a special ceremony to ensure there is no
ambiguity. <br><br>
And certainly a collection of entities may be an entity. Thus
'Senate of the United States' is, in the context of our Constitution, an
unambiguous identifier for a collection of one hundred persons (sometimes
less, never more).<br><br>
Obviously folks sometimes say 'URI' when they mean "sequence of
characters matching the syntax rule." And that's fine in a
conversation where precision of terminology is not required or even
useful. And it is fine in a conversation where it gives as much
precision as is needed. But it helps to have a well defined jargon,
and to stick to it when it is useful.<br><br>
It's fine for me and you (no insult intended, if you are a sailor) to
refer to a line using 'rope', but if we are on deck in a storm, it is not
best for us to holler to the captain through the wind "A rope has
broken", when she needs to know immediately whether the line that
has parted is a sheet, a halyard, a shroud, something else essential, or
merely a ratline.<br><br>
Cordially, Joaquin<br><br>
<font face="Times New Roman, Times" size=3>The answer to the question in
the Subject is: Yes.<br><br>
<br>
<blockquote type=cite class=cite cite="">... there are no identifiers
except in relation to a naming context. With respect to a given
naming context, an identifier is a name for a single entity. If, in
a given naming context [and at the same time], a name refers to two or
more entities, that name is not an identifier.<br>
<br>
Cordially, Joaquin<br><br>
I feel it would be a waste of our time, but if challenged I can quickly
demonstrate that there is no such thing as an identifier that is
unique. My point about 'unique identifier' is that it muddles the
conversation and sows confusion. But another point is this: It's
not useful to call an identifier that is not unique a 'unique
identifier'. </font></blockquote></body>
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