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Re: RFC 2141 on URN Syntax

From: Sukanta Ganguly <SGANGULY@novell.com>
Date: Fri, 09 May 1997 08:54:29 -0600
Message-Id: <s372e666.061@novell.com>
To: ejw@ics.uci.edu
Cc: w3c-dist-auth@w3.org
  I wanted to mention some things about the rfc 2141 that I found confusing.
I feel that the details should be verified.

The syntax for a URN is specified as
<URN> ::= "urn:" <NID> ":" <NSS>
and NSS also has ":" as a characters recognized within the <others> rule.
Based on this
    URN:foo::      -> Is this a valid URN ??

I feel that is ":" is used as a reserved terminator of a subsection of a
rule then it should not be used in the recognized character sets for the
other sub-sections of the rule. So I would imagine that ":" is not present
as a recognizable character within the <other> rule of NSS subsection.

It just adds an extra amount of parsing effort for the applications to have
this feature in their parsing mechanisms. I don't say that it is impossible
to have it, but as a application developer, it  would be a much messy
approach for me to write code that has this feature in it. I hope this not
taken as a negative criticism. 

I have a similar concern regarding the usage of "%" character within the
<NSS> subsection. This is what the rule resolution says 
<NSS> ::= 1*<URN chars>
<URN chars> ::= <trans> | "%" <hex> <hex>
<trans> ::= <upper> | <lower> | <number> | <other> | <reserved>
<reserved> ::= '%" | "/" | "?" | "#"

Here we observe that 

  <NSS> ::= %    could be a valid rule according to the  rule definition. At
the same time the system has another defination that says wheneever "%" is
used two  <hex> characters should be used.

  <NSS> ::=%%12  -> could also be a valid syntax for NSS.  

My suggestion here is to remove "%" from the <reserved> subsection of <NSS>

Please let me know if my thinking is along the lines of what the group has
in mind or am I way out of wack. I appreciate your acceptance of my
participation in the group.

Thank You
Sukanta Ganguly

>>> Jim Whitehead <ejw@ics.uci.edu> 05/06/97 12:07PM >>>

Of potential interest to participants of this WG.

- Jim

>To: IETF-Announce: ;
>Subject: RFC 2141 on URN Syntax
>Cc: rfc-ed@isi.edu 
>Mime-Version: 1.0
>Date: Mon, 05 May 97 13:53:28 PDT
>From: RFC Editor <rfc-ed@isi.edu>
>A new Request for Comments is now available in online RFC libraries.
>        RFC 2141:
>        Title:      URN Syntax
>        Author:     R. Moats
>        Date:       May 1997
>        Mailbox:    jayhawk@ds.internic.net 
>        Pages:      8
>        Characters: 14077
>        Updates/Obsoletes: None
>        URL:        ftp://ds.internic.net/rfc/rfc2141.txt 
>Uniform Resource Names (URNs) are intended to serve as persistent,
>location-independent, resource identifiers. This document sets
>forward the canonical syntax for URNs.  A discussion of both existing
>legacy and new namespaces and requirements for URN presentation and
>transmission are presented.  Finally, there is a discussion of URN
>equivalence and how to determine it. This document is the product of
>the Uniform Resource Names Working Group of the IETF.
>This is now a Proposed Standard Protocol.
>This document specifies an Internet standards track protocol for the
>Internet community, and requests discussion and suggestions for
>improvements.  Please refer to the current edition of the "Internet
>Official Protocol Standards" (STD 1) for the standardization state and
>status of this protocol.  Distribution of this memo is unlimited.
>This announcement is sent to the IETF list and the RFC-DIST list.
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Received on Friday, 9 May 1997 10:57:03 UTC

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