Multiple rft_id's is a fine solution to isbn for a book citation---but if you've got an article citation, that lives in a particular journal with an issn, and you know the issn of that journal---please don't put it in a rft_id. An ISSN is not a good identifier for one particular article IN the journal. Some openurl providers (such as, as it happens, certain OCLC services) send an ISSN in an rft_id for an article citation (rather than a journal citation), which confused my software terribly until I figured out what was going on.
So, as far as I know, there's no good solution to providing multiple known ISSNs on an article-level citation. Repeatable _referent_ (in SAP2) isn't really a proper solution either; we are talking about one referent with multiple known ISSNs.
>>> Eric Hellman <[log in to unmask]> 02/28/08 12:46 PM >>>
Worldcat Link Manager will use the last valid (including check digit)
ISBN in the OpenURL, whether in an rft_id or in an rft.isbn. Currently
xISBN is used in the response if it is turned on. Multiple rft_id is
valid according to spec.
On Feb 19, 2008, at 9:26 AM, Ross Singer wrote:
> Actually, this:
> indicates that multiple rft_ids *are* valid, and, in fact, would have
> to be, since you could very easily have a DOI and a PMID and, say, a
> I have no idea what any resolver would do with this bundle of ISBNs,
> of course. It also seems somewhat contrary to the intention of the
> Book metadata format, since I think it's (in my murky view of FRBR-y
> terms) trying to define a manifestation rather than the expression
> level that Bill is trying to use it for. I could be weaving in my own
> interpretations and biases there.
> An alternative would be use by-reference context objects and then make
> the context objects available as XML. You could have multiple context
> object available in one XML document this way. A combination of
> COinS/unAPI could make something like this possible.
> On Feb 18, 2008 6:53 PM, Karen Coyle <[log in to unmask]> wrote:
>> Actually, the max occurrence of ALL of the KEV keys is 1 except for
>> (which is unlimited). I remember discussions in which we acknowledged
>> that one key NE one value, eg you could input multiple values if your
>> recipients were in agreements (a poor excuse, I know). Thus:
>> "isbn:3333;isbn:8888". My only memory for why max=1 for all of
>> these is
>> that it has to do with the fact that there is no structure or
>> in KEV, so an OpenURL with keys
>> isn't interpretable in terms of what authors go with what titles. Why
>> the exception for au but for no other fields? My memory fails me
>> Undoubtedly it made sense at the time.
>> Jay Luker wrote:
>>> Hi William,
>>> According to the book KEV format (defined here:
>>> ttp://tinyurl.com/2psmkq) the max occurrence of the isbn key is 1.
>>> assuming that by extension that means that the rft.<m-key> (i.e.,
>>> rft.isbn) form is also limited to one occurrence. So specifying
>>> multiple ISBNs that way is a no go.
>>> You can however specify multiple referent identifiers. From the KEV
>>> Context Object format matrix (http://tinyurl.com/2r5hsc): "Multiple
>>> instances of rft_id do not indicate multiple Referents, but rather
>>> multiple ways to identify a single Referent"
>>> So I *think* what you could do is this:
>>> Also, I'd be remiss not to point you to a more authoritative list
>>> OpenURL questions: http://listserv.oclc.org/scripts/wa.exe?A0=OPENURL
>>> Although I'm sure there's plenty of overlap in interest/knowledge in
>>> the subject between the lists.
>>> Jay Luker [log in to unmask]
>>> Software Engineer, Ex Libris Inc.
>>> (617) 332-8800, x604 http://www.exlibrisgroup.com
>>> On Feb 17, 2008 3:14 AM, William Denton <[log in to unmask]> wrote:
>>>> I'm hep to the COInS scene now and am using it in some lists of
>>>> books I'm
>>>> generating. For some of the books I know multiple ISBNs. Can I
>>>> them all in one COInS span somehow? Doing one individually makes
>>>> OpenURL Referrer extension clutter up the page with a lot of links.
>>>> I looked at the specification but it didn't seem to cover this.
>>>> generator.ocoins.info only seems to want one one ISBN. Putting
>>>> rft.isbn variables just makes the last one overpower the earlier
>>>> Any tips appreciated!
>>>> William Denton, Toronto : www.miskatonic.org www.frbr.org www.openfrbr.org
>> Karen Coyle / Digital Library Consultant
>> [log in to unmask] http://www.kcoyle.net
>> ph.: 510-540-7596 skype: kcoylenet
>> fx.: 510-848-3913
>> mo.: 510-435-8234