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What's a Referrer?

From: Terry Allen <tallen@fsc.fujitsu.com>
Date: Tue, 28 Jan 1997 11:42:48 -0800 (PST)
Message-Id: <199701281942.LAA24180@ishtar.fsc.fujitsu.com>
To: w3c-sgml-wg@www10.w3.org
What's a Referrer?

Section 4.2 reads:

| Many addressing mechanisms assume the existence of some sort of a base 
| address whose value effects the interpretation of the address. To 
| formalize this, every HREF has a location source, an object or objects 
| which serves as the base address. In most cases the location source can 

"base address" needs definition.

| be omitted and is implied to be the document element of the document 
| that contains the link. However, this implied location source can also 
| be specified as being the non-link element that refers to the link 
| element (the referrer).

What does that last sentence mean?  And if the "implied location source"
(a.k.a. "base address", which is more homey) is specified, in what
manner is it still implied?  What is the reason for having both
locsrc and implied-locsrc?  And it seems as though the "base address" 
may vary with each occurrence of a link element.  Do we need that?

| The location source is specified using the the location-source 
| attribute. The format of the location-source string is not specified; to 
| be useful, clearly it must be in a form that can be processed by the 
| processor that can deal with the HREF and reference type to which it is 
| attached. If the location-source attribute is omitted, the location 
| source is implied according to the rule indicated by the IMPLIED-LOCSRC
| attribute.

This implies that every HREF value has a "base address", whether the
author intended to employ such a mechanism or not.  I wouldn't be
surprised if that assumption screws up some addressing scheme,
though I don't have one in mind.  Perhaps this should be qualified
such that a "base address" is implied only if HRTYPE is an 
addressing scheme that uses a relative addressing mechanism.

Also, the punt on the format of the string is unsatisfactory.  We
won't get interoperability unless we can say what the format must be;
if this varies with HRTYPE then reference should be made to some
canonical statement of what a "base address string" is for that
HRTYPE (for HRTYPEs the use of which is anticipated) or it should
be said that the specification of HRTYPEs that use relative addressing must 
include an unambiguous specification of "base address string" for
that HRTYPE.  Note that HRTYPEs not mentioned in this spec will not
be implemented by all implementors.

    Terry Allen    Fujitsu Software Corp.    tallen@fsc.fujitsu.com
"In going on with these experiments, how many pretty systems do we build,
 which we soon find outselves obliged to destroy?" - Benjamin Franklin
  A Davenport Group Sponsor:  http://www.ora.com/davenport/index.html
Received on Tuesday, 28 January 1997 14:43:24 UTC

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