Scott,

  As you noticed on the LC web site, we have experimented with getting
links to HTML documents from EAD.

  We tried creating a NOTATION declaration for HTML, which you show in
your message.  The box you get in Panorama is because Panorama probably
doesn't know what to do with that non-SGML type (using NDATA).  Usually
you have to create an entry in the Panorama "setup" file to tell Panorama
what to do.

  Instead of using this approach, we used the Panorama processing
instructions that have been mentioned in an earlier response to your
message.

  I am including notes from our testing.  One of the problems we haven't
dealt with is how get back to Panorama after linking to the
HTML homepage.  For the interim, you can use the ALT+TAB key combination
to get back to Panorama (Windows 3.x) or click on the SoftQuad Panorama
button on the Windows task bar (Windows 95).

<notes>
Linking to a homepage
---------------------

We know from the NAACP finding aid test that we have two ways to link
to a homepage using Panorama Pro processing instructions.

1) add <?TAGLINK ref URI> to the finding aid and refer to the homepage
with <ref>http://lcweb.loc.gov/rr/print/</ref>

OR

2) add <?ATTLINK exptr ext.ptr URI> to the finding aid and refer to the
homepage with <extptr ext.ptr="http://lcweb.loc.gov/rr/print">

Use of Indirection
------------------

Whichever method you select (using element content or the value of an
attribute), you can remove the "hard-coded" URL from the SGML document.

1) identify where you want the link in the finding aid:

   <ref>&homelnk;</ref>

   OR

   <extptr ext.ptr="&homelnk;">

2) add an external entity to the finding aid:

   <!DOCTYPE ead PUBLIC <!-- public identifier deleted for example -->
   [
   <!ENTITY % eadlink SYSTEM "eadlink.ent"  >
   %eadlink;
   ]>
   <?ATTLINK extptr ext.ptr URI>
   <?TAGLINK ref URI>
   <ead>   ...  </ead>

3) create a file, eadlink.ent, that contains:

   <!ENTITY homelnk "http://lcweb.loc.gov/rr/print/"  >

</notes>

   You can, of course, use other EAD elements.  When we did our testing
here, we were specifically looking at <ref> and the ext.ptr attribute of
<extptr>.  The processing instructions will have to change depending on
which elements/attributes you use.


On Mon, 19 May 1997, Scott Alan Leonard wrote:

> I'm still working on getting links to HTML documents from EAD.  I've
> followed Daniel Pitti's advice and looked at his EAD Retrospective
> Conversion Guidelines (http://sunsite.berkeley.edu/amher/upguide.html;
> thanks Stephen).  I'm not sure what I'm doing wrong, but the EAD document
> doesn't create a link from the text to the HTML document.  This is what
> I'm doing:
> [(...text snipped...)
> <!NOTATION html PUBLIC "-//IETF//DTD HTML/EN">
> <!ENTITY accessuse PUBLIC "-//(..text snipped...)//TEXT
> (URL of HTML document)//EN" NDATA HTML>
> ]
> (...text snipped...)
> ... see <extref displaytype="present" entityref="accessuse"> Policy on
> Access and Use</extref>.
>
> When Panorama loads the SGML document, before the words "Policy on Access
> and Use" there appears a box with the NOTATION and ENTITY declarations in
> it (this box is similar to the box that I saw when I discovered that
> PanoramaFree 1.0 doesn't read JPEG images). The text "Policy on Access and
> Use" is the text that I want to link from to the URL of the HTML document.
>
> The Coversion Guidelines seem rather vague about external pointers.  The
> section on the <dao> element was clear to me, but the rest of the
> information feels more like a lesson on how to tag using the given
> elements.  (The information on the <ref> element is clearer, but appears
> to belong in the internal pointers section.)
>
> The Panorama manual talks about linking to URLs, using <?ATTLINK tagname
> attname URI> elements (this causes Panorama to treat the value of
> attribute "attname" of the element "tagname" as a URL), but this doesn't
> work much better.  I attempted to go this way before, but it lead to a
> deadend where it brought up part of the text from the HTML document within
> the SGML browser.
>
> Has anyone linked to HTML documents from within the EAD?  If so, please
> let me know where I can look at an example.  LC's "Visual Materials of the
> NAACP" implies a future link to the Prints and Photographs home page, but
> the link is still under construction.
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Scott A. Leonard  ><>
> e-mail:  [log in to unmask]
> Scott's Page on the Web:  http://www.wam.umd.edu/~sleonard/
>
>     "I cannot speak for the way God deals with others; I know only how He deals
> with me personally."
>                                 C. S. Lewis,  _God in the Dock_ (p. 262)
>


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Marla Thomas Banks                  email: [log in to unmask]
Information Technology Services     phone: (202) 707-9631
Library of Congress                 Fax    (202) 707-0955
Washington, DC 20540-9332

  Disclaimer: The opinions expressed here are my own
              and do not necessarily represent those of
              the Library of Congress.
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