Perhaps this has already been covered...
but just as an example, we chose to include the
Processing Instruction in the document type
declaration subset of each of our instances
(i.e. at the top of every file).

Here is the complete wording of the declaration subset
we use - with the EXTREF declaration in place:

(A word of caution: as with coding, SGML parsers are unforgiving if
even a single piece of punctuation is out of place.)

<!DOCTYPE EAD PUBLIC "-//Society of American Archivists//DTD ead.dtd
(Encoded Archival Description (EAD))//EN" "ead.dtd"
[<!ENTITY brblmain SYSTEM "../otdf/brblmain.gif" NDATA gif>]>
<?STYLESPEC "Beinecke Library Style Sheet" "../otdf/beinecke.ssh">
<?NAVIGATOR "Beinecke Library Navigator" "../otdf/beinecke.nav">
<?ATTLINK extref ext.ptr URI>


Timothy Young
Beinecke Rare Book and Manuscript Library
Yale University
New Haven, CT  06520
(203) 432-8131

At 12:46 PM 3/26/98 -0500, you wrote:
>Naomi Nelson write:
>> Based on the Griffis project, it appears that to link an EAD-encoded
>> finding aid to a digital object (using Author/Editor) one must create an
>> entity and then enter the entity name in the EXT.PTR attribute for the
>> EXTREF.  Having done so, however, I am still unable to view a jpeg in
>> same directory as the finding aid.  What am I doing wrong?
>There's also a configuration setting, an SGML Processing Instruction,
>necessary to tell Panorama what to do with the information provided in the
>entity. If the entity points to a document on the web, a PI can be used to
>set Panorama to treat it as a link. (If preferred, Panorama's entityrc
>file can be used to associate the PI with all documents using the DTD, in
>lieu of hard-coding it in the document.) If the entity points to a file in
>a format Panorama can handle in its graphic viewer (as of Panorama 1.5
>this included gif but not jpeg images; I think they have broader support
>now), an SGML NDATA (NOTATION) attribute can be used to enable Panorama to
>do so.
>This involves some careful work in site configuration as well as making
>sure the various settings are correct. Panorama documentation tells how to
>do it in greater detail.
>Unfortunately, this is an application-dependent method of creating the
>link (though relying on standard SGML constructs): it works only for
>Panorama. With XML and XLL (XML linking) coming along, there will likely
>be other methods emerging to do the same thing in other applications.
>While we can congratulate ourselves that our data, at least, should be
>stable, we may have to resign ourselves (at least for now) to a periodic
>redesign of the infrastructure within which the data are presented....
>Wendell Piez
>[log in to unmask]
>    "Thus I make my own use of the telegraph, without consulting
>     the directors, like the sparrows, which I perceive use it
>     extensively for a perch." -- Thoreau