More on Scan

Looking at the Scan response ASN.1, the definiton of ListEntries at
	http://lcweb.loc.gov/z3950/agency/asn1.html#ListEntries
says that the "entries" element is OPTIONAL.  Is there any reason for
this?  The prose at
	http://lcweb.loc.gov/z3950/agency/markup/05.html
(section "3.2.8.1.7 Entries", near the bottom of the page) says:

	The parameter Entries returned by the target consists of one
	of the following:

	* N entries, where each entry is a term-list-entry or
	  surrogate diagnostic, where N = Number-of-entries in the
	  request.
	* A number of entries which is less than N, and may be zero
	  (reason specified by Scan-status).

	And may also include:

	* One or more non-surrogate diagnostic records (possibly
	  indicating that the operation cannot be processed, and why
	  it cannot).

Which says to me that the entries are mandatory?

Also, does anyone have a server that, as this prose allows, returns
responses containing both a list of entries _and_ non-surrogate
diagnostics?  Isn't the whole point of non-surrogate diagnostics that
you get them when an entire request fails?

In other words, wouldn't it have been more logical to define
ListEntries as a CHOICE?

Thanks to all for helping me wrap my head around this stuff.  I should
have done it years ago.

BTW., thanks to all of you who offered me the details of scan-capable
servers that I can test against.  I thanked some of you individually,
but not all.  It's been very helpful having them available.

 _/|_	 _______________________________________________________________
/o ) \/  Mike Taylor  <mike@indexdata.com>  http://www.miketaylor.org.uk
)_v__/\  "It became necessary to destroy the village in order to save
	 it" -- Attributed to an anonymous senior US military officer.

--
Listen to my wife's new CD of kids' music, _Child's Play_, at
	http://www.pipedreaming.org.uk/childsplay/

Received on Wednesday, 5 May 2004 17:17:57 UTC