Creating External Links and In-Line Images in OASIS Finding Aids
The EAD tag library contains many linking elements, but OASIS supports only four:
- <dao> digital archival object
- <daogrp> the digital archival object expressed as a group of <daoloc>s
- <extref> the extended reference, and
- <extptr> the extended pointer
Implementation of these elements makes use of their attributes and subelements. Linking elements are used for both "clickable" access to a web resource and to display imbedded or "inline" images.
Results of clicking on a link can be customized by the functionality available in the system to which the link points (for example, limiting access to a resource described in a finding aid to Harvard users only could be accomplished by pointing to a resource in the DRS, from which access can be configured to display to a) anyone b) only those within Harvard University.) Thus, it is important to take into account such customizations in the finding aid.
Note: An "inline" image is an image that is intrinsically
part of a document, like this image, 
as opposed to
an external image that is made visible by clicking on a link.
Definition of linking elements
About the actuate and show attributes
Functionality in Digital Only View
Definition of Linking Elements
- <daogrp>/<daoloc>/<daodesc>
A <daogrp> wraps multiple links to the same archival item. It contains <daoloc>s, each of which contains a link to a surrogate of the same object. An example of this is a thumbnail image that links to a higher-resolution image. - <dao>/<daodesc>
A <dao> can be:- an in-line "non-clickable" image
- a text hyperlink to a digital object
- <extref>/<extptr>
An <extref> that contains an <extptr> is used to create an image that is also an active link. This combination of elements is used wherever the EAD.DTD or EAD.XSD does not permit <daogrp>. - <extptr>
An <extptr> used alone will display images that are not links. Examples of this include a "non-clickable" display of your institution's shield or a small portrait of the collection originator.
These sets of linking elements have similar functionality, but are valid in different contexts in the EAD DTD/Schema. There seems to be no theoretical basis for the distinction.
About the actuate and show attributes
Note that the actuate and show attributes control link behavior.
<daogrp>
<daoloc show="embed" actuate="auto">
The first <daoloc> with these attributes is the embedded object (for example, a thumbnail image)
<daoloc actuate="user">
The first <daoloc> with this attribute is the on-line resource reached by clicking on the embedded object (for example, a medium-resolution version of the embedded image)
<daoloc actuate="user">Any subsequent <daoloc> with this attribute becomes available through a hyper-text link on a separate line below the in-line object (for example, a high-resolution version of the embedded image).
The default text for the link will be whatever is the value of the href attribute. Any custom text for this hyper-link is encoded in the <daodesc> element.
<dao actuate="auto" show="embed">
The image displays automatically, or a music or video file plays automatically, when the finding aid is loaded.
Note: This is the same behavior as <extptr>, but <dao> is needed because there are places where the DTD or Schema permits <dao> and does not permit <extptr>.
<dao actuate="user" show="new">
A hyperlink is created. The "clickable" text is the content of <daodesc> if it is present, or the value of the href attribute if it is not. When the user clicks on the link, the new content will open up in a new window.
<dao actuate="user" show="replace">
The same as above except, when the user clicks on the link, the new content will replace the parent frame.
<extref actuate="user" show="replace">
When the user clicks on the link, the new content will replace the parent frame.
<extref actuate="user" show="new">
When the user clicks on the link, the new content will open up in a new window.
Note: This is the default behavior if no attributes are given.
<extptr actuate="auto" show="embed">
This is the only combination of attributes for <extptr> that OASIS supports. The image displays automatically, or a music or video file plays automatically, when the finding aid is loaded.
Functionality in Digital Only View
The OASIS Digital Only View is a separate view of the finding aid that is limited to materials in digital form. The Digital Only View is available only for finding aids that contain links out to digital materials and/or embedded thumbnail images. The XML elements that qualify for Digital Only View are any daogroup/daoloc and dao (within a "c" element) which has an @href attribute (which is the actual url of the link or thumbnail).
The Digital Only View includes some contextual text for the digital materials. This includes frontmatter and archdesc/did. For each item-level "c" element containing one or more dao or daogroup (with href attribute), text from the following elements (and child elements), if present, will be displayed:
Above the link/thumbnail:
- dsc/head (parent)
- c/did/unittitle (parent and self)
- c/did/unitid (parent and self)
- c/did/unitdate (parent and self)
- c/did/head (parent and self)
- c/did/physdesc (self)
- c/note (self)
Below the link/thumbnail:
- daodesc (may be clickable)
Formatting and nesting of these specific elements will appear the same as on the Full Finding Aid view.
Shields Examples 1-2
Links to repository Examples 2-3
External links from text
Examples 4-6
External links from embedded thumbnails Examples 7-11
Links within the same finding aid Example
12
Links to other finding aids Examples 13-14
Nota bene: To use the examples below, you may copy the encoding and then paste it into your EAD finding aid. Remember to replace the value in the href attribute with the URL or URN of your own resource.
Example 1. Display a shield image
XML Encoding:
<extptr href="http://nrs.harvard.edu/urn-3:HUL.OIS:hu_archive_shield" inline="true"/>
OASIS Result:
Example 2. Display a shield image that is also a link
XML Encoding:
<extref href="http://nrs.harvard.edu/urn-3:hul.eresource:archives" actuate="user" inline="true">
<extptr href="http://nrs.harvard.edu/urn-3:HUL.OIS:hu_archive_shield" actuate="auto" inline="true"/>
</extref>
OASIS Result:
Example 3. Link to a repository name in the <archdesc> <did>
XML Encoding:
<repository>
<extref href="http://nrs.harvard.edu/urn-3:hul.eresource:archives" inline="true"> Harvard University Archives </extref>
<repository>
OASIS Result:
Repository: Harvard University Archives
Example 4. Link to an archival object from unittitle text in a folder list
XML Encoding:
<c level="item">
<did>
<unittitle>
<extref href="http://nrs.harvard.edu/urn-3:HUL.ARCH:kate" show="new" actuate="user" inline="true">Kate, 1999</extref>
</unittitle>
</did>
</c>
OASIS Result:
Example 5. Link to an archival object from unitid text in a folder list (music file example)
XML Encoding:
<c level="item">
<did>
<unitid>
<extref href="http://nrs.harvard.edu/urn-3:FHCL.Loeb:sa11" show="replace" actuate="user" inline="true"> [awm rl 15027 (1)]
</extref>
</unitid>
<unittitle>Tolling of bells on Mt. Athos </unittitle>
</did>
</c>
OASIS Result:
- [awm rl 15027 (1)] Tolling of bells on Mt. Athos
Example 6. Link to an archival object from "clickable" added text in a folder list
XML Encoding:
<c level="item">
<did>
<unittitle>Kate, 1999</unittitle>
<dao href="http://nrs.harvard.edu/urn-3:HUL.ARCH:kate" show="new" actuate="user" inline="true">
<daodesc>
<p>Click here to see image.</p>
</daodesc>
</dao>
</did>
</c>
OASIS Result:
- Kate, 1999 Click here to see image.
Example 7. Embed a "non-clickable" thumbnail in a folder list, thumbnail and large image based on a single image file
XML Encoding:
<c level="item">
<did>
<unittitle>Kate, 1999</unittitle>
</did>
<dao href="http://nrs.harvard.edu/urn-3:HUL.ARCH:kate" height="250" show="embed" actuate="auto" inline="true">
</dao>
</c>
OASIS Result:
- Kate, 1999
Example 8. Embed a "clickable" thumbnail in a folder list
XML Encoding:
<c level="item">
<did>
<unittitle>Kate, 1999</unittitle>
<daogrp inline="true">
<daoloc href="http://nrs.harvard.edu/urn-3:HUL.ARCH:kate" height="250" show="embed" actuate="auto">
</daoloc>
<daoloc href="http://nrs.harvard.edu/urn-3:HUL.ARCH:kate" show="new" actuate="user">
<daodesc>Click for larger view</daodesc>
</daoloc>
</daogrp>
</did>
</c>
OASIS Result:
- Kate, 1999
Click for larger view
Example 9. JPEG 2000 images with zoom
XML Encoding:
<c level="item">
<did>
<unittitle>8th Graduating Class Chaplains School, Harvard University, Cambridge, Massachusetts, 1943 </unittitle>
</did>
<daogrp inline="true">
<daoloc actuate="auto" href="http://nrs.harvard.edu/urn-3:HUL.ARCH:155548?height=100" show="embed"/>
<daoloc actuate="user" href="http://nrs.harvard.edu/urn-3:HUL.ARCH:155548?buttons=y" show="new">
<daodesc><p>Click for larger view</p></daodesc>
</daoloc>
</daogrp>
</c>
OASIS Result:
- 8th Graduating Class Chaplains School, Harvard University, Cambridge, Massachusetts, 1943
Click for larger view
Example 10. Link to images of differing resolutions
<c level="item">
<did>
<unittitle>Agnes Mongan aboard the Amsterdam, ca. 1950 </unittitle>
</did>
<daogrp inline="true">
<daoloc actuate="auto" href="http://nrs.harvard.edu/urn-3:huam:77770_smdl" show="embed"/>
<daoloc actuate="user" href="http://nrs.harvard.edu/urn-3:huam:77770_mddl" show="new">
<daodesc><p>Click for medium-resolution image</p></daodesc>
</daoloc>
<daoloc actuate="user" href="http://nrs.harvard.edu/urn-3:huam:77770_lgdl" show="new">
<daodesc><p>Click for high-resolution image</p></daodesc>
</daoloc></daogrp>
</c>
OASIS result:
-
Agnes Mongan aboard the Amsterdam, ca. 1950
Click for medium-resolution image
Click for high-resolution image
Example 11. Houghton thumbnail and link
<c level="item">
<did><unitid id="hou00121f706-2">(706.2)</unitid>
<unittitle>
<persname>Ralph Waldo Emerson </persname>
<unitdate type="single">ca. 1848.</unitdate>
<genreform>Daguerreotype: </genreform>quarterplate; oval frame, case.
</unittitle>
</did>
<note>
<p>Possibly by <corpname>Southworth & Hawes,</corpname>photographer. </p>
</note>
<daogrp>
<daoloc href="http://nrs.harvard.edu/urn-3:FHCL.Hough:49071" show="embed" actuate="auto">
</daoloc>
<daoloc actuate="user" show="new" href="http://nrs.harvard.edu/urn-3:FHCL.Hough:31882">
<daodesc>
<p>Click for larger view </p>
</daodesc>
</daoloc>
</daogrp>
</c>
OASIS Result:
- (706.2) Ralph Waldo Emerson ca. 1848. Daguerreotype:
quarterplate; oval frame, case.
Possibly by Southworth & Hawes, photographer.
Click for larger view
Example 12. Linking within a finding aid
- See Internal Links in Finding Aids for information on linking from one place in a finding aid to another place in the same document.
Example 13. Linking to another OASIS finding aid
(These links go from anywhere in a finding aid to the top of another finding aid. It is not possible to link to a specific section of an OASIS finding aid, unless the link is coming from within the same document, as in example 12.)
XML Encoding:
<relatedmaterial>
<p>
Records of the Division of Engineering and Applied Physics (UAV 362.5xxx),
<extref href="http://nrs.harvard.edu/urn-3:HUL.ARCH:hua15001">
Records of the Harvard Underwater Sound Laboratory
</extref>
(UAV 859.xx), and the General Office Files of the
<extref href="http://nrs.harvard.edu/urn-3:HUL.ARCH:hua01999">
Records of the Dept. of Physics
</extref>
(UAV 691) in the Harvard University Archives.
</p>
</relatedmaterial>
OASIS result:
Related Materials
Records of the Division of Engineering and Applied Physics (UAV 362.5xxx), Records of the Harvard Underwater Sound Laboratory (UAV 859.xx), and the General Office Files of the Records of the Dept. of Physics (UAV 691) in the Harvard University Archives.
Example 14. Linking to a finding aid outside OASIS
XML Encoding:
<relatedmaterial>
<p>
Papers of Ida Pruitt housed in other repositories include IP's papers re: the
Chinese Industrial Cooperatives at the Special Collections at Columbia University
and three folders of Ida's correspondence (1938-1952, undated) in the
<extref href="http://www.nypl.org/research/chss/spe/rbk/faids/russell.htmlquot;>
Maud Russell collection
</extref>
at the New York Public Library.
</p>
</relatedmaterial>
OASIS result:
Related Materials
Papers of Ida Pruitt housed in other repositories include IP's papers re: the Chinese Industrial Cooperatives at the Special Collections at Columbia University and three folders of Ida's correspondence (1938-1952, undated) in the Maud Russell collection at the New York Public Library.