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Re: Can anyURI be empty?

• To: "Thomas B. Passin" <tpassin@c...>
• Subject: Re: Can anyURI be empty?
• From: Bob Foster <bob@o...>
• Date: Tue, 06 Apr 2004 23:48:48 -0500
• Cc: xml-dev@l...
• In-reply-to: <40737DAB.9050205@c...>
• References: <520E883A6B222B41BDDF18CBAAF0847C05ABBC23@c...> <40733F33.3060205@c...> <BAY9-DAV65hmCtZ1eEX0001f6a3@h...> <4073677A.2090606@o...> <40737DAB.9050205@c...>
• User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.5) Gecko/20031007

Thomas B. Passin wrote:
 > Bob Foster wrote:
 >
 >> Joe Fawcett wrote:
 >>  > I'm having trouble working out from
 >>  > http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/#anyURI
 >>  > [shown at bottom of mail]
 >>  > means that anyURI can be an empty string, can someone elucidate?
 >>
 >> If it couldn't, it would be wrong. An empty string is a valid URI.
 >>
 >
 > How's that?  RFC 2396 requires a scheme followed by a colon (for an
 > absolute URI), or at least one character for a relative URI -
 >
 >     rel_path      = rel_segment [ abs_path ]
 >
 >     rel_segment   = 1*( unreserved | escaped |
 >                           ";" | "@" | "&" | "=" | "+" | "$" | "," )
 >
 > So you have to have at least one character...

I certainly don't fault you for this comment. RFC 2396 should earn its 
place in history as an example of how not to write a specification mere 
mortals can understand. Here's the relevant part:

"C.2.  Abnormal Examples

    "Although the following abnormal examples are unlikely to occur in
    normal practice, all URI parsers should be capable of resolving them
    consistently.  Each example uses the same base as above.

    "An empty reference refers to the start of the current document.

       "<>            =  (current document)"

The RFC specifically allows for an empty reference; in fact, it defaults 
to an empty reference (5.2.7).

Bob Foster
http://xmlbuddy.com/

• Follow-Ups:
  • Re: Can anyURI be empty?
    • From: "Thomas B. Passin" <tpassin@c...>

• References:
  • XML question - reference points
    • From: "Pascarella, Randy" <randall.pascarella@h...>
  • Re: XML question - reference points
    • From: "Thomas B. Passin" <tpassin@c...>
  • Can anyURI be empty?
    • From: "Joe Fawcett" <joefawcett@h...>
  • Re: Can anyURI be empty?
    • From: Bob Foster <bob@o...>
  • Re: Can anyURI be empty?
    • From: "Thomas B. Passin" <tpassin@c...>

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