Data Creation
Linking to digital content: <dao> options
Digital Archival Objects are electronic representation of the described archives. The Hub provides a number of options for displaying and linking to digital archival objects.
Please Note: images and files must be stored somewhere that provides a stable URL for them. The Archives Hub cannot store your objects, so you need to ensure that they are uploaded to an accessible server.
- Create a link to a digital object
- Embed an image to display in the description
- Link to more than one file or display more than one image
- Grouping objects
- Display a thumbnail image that links to a full-size image/file
- Display a single conceptual object with multiple digital surrogates
The information given below refers to the tags used and how to use them. If using the Archives Hub EAD Editor to create and edit records contributors do not need this understanding of the tags as the template provides the appropriate labelled boxes for information entry.
Create a link to a digital object
Link to single files, such as PDF transcripts of text documents or word-processed documents.
Note that the 'show' attribute needs to be set to "new" rather than "embed". This is done automatically when using the Hub EAD Editor.
<dao href="http://domain.ac.uk//full-text.pdf" show="new" title="View full text (PDF)" />
or (with descriptive text)
<dao href="http://domain.ac.uk/full-text.pdf" show="new" title="View full text (PDF)">
<daodesc><p>PDF transcription of a letter</p></daodesc> </dao>
You can include links to audio files such as MP3 files. The way that these work for Hub users will depend upon their browser set-up.
Embed an image to display in the description
Single images can be embedded into the Hub display either at collection-level or lower-levels (e.g. item level)
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Images can be added in the <did> section (core information) or at the top level of <archdesc>. If they are added to other tags they may not display on the Hub.
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The format should be jpg, gif or png.
Use a single <dao> element to represent the Digital Archival Object. The location of the object is provided in the HREF attribute. The 'show' attribute is used to either display the resource at the point of the link (embed) or display it in a new window (new).
<dao href="http://host/images/myimage.jpg" show="embed" />
The <dao> tag may also contain a <daodesc> tag, with a short caption for the image which will be displayed alongside the image on the Hub. The tag should include an opening and closing <p> tag to denote a paragraph
<dao href="http://host/images/myimage.jpg" show="embed">
<daodesc><p>Photograph of Notebook</p></daodesc> </dao>
However, if the unittitle of the collection or component is sufficient to identify the digital object, a <daodesc> caption is not necessary.
Image Size: Images don't currently resize, and there isn't provision in EAD to provide this. Please do not embed large images, but use the supported thumbnail link to full-size image approach instead (see below).
The Hub constrains the amount of screen width that the images are permitted to occupy, and scrolling allows the user to view the rest of the image, but it is preferable to use a smaller image that does not require scrolling. Recommended maximum image size is 200 pixels (at standard resolution of 72 dpi).
Link to more than one file or display more than one image
You can include a number of <dao> entries in your description, each with a separate <daodesc>. The images or links will display in a vertical box running down the length of the description.
Please remember that <daogrp> is used for a group of digital objects that represent the same entity, sharing the same digital archival object description (see below)
Grouping objects
It is possible to group images using the wrapper element <daogrp>. This may contain two or more digital archival object locations <daoloc> which share the same description <daodesc>. <daogrp> may not contain <p> tags - these must be within the <daodesc> tags.
Display a thumbnail image that links to a full-size image/file
Here the thumbnail image, labelled as "thumb", links to a full size image, labelled as "reference", with descriptive text displaying with the embedded image:
<daogrp>
<daodesc><p>A black & white photo depicting the business.</p></daodesc>
<daoloc href="http://host/images/hwud11001_small.jpg" role="thumb" />
<daoloc href="http://host/images/hwud11001_full.jpg" role="reference" />
</daogrp>
The recommened maximum size for thumbnail images is 180px square.
Display a single conceptual object with multiple digital surrogates
The <daogrp> is a wrapper element that contains two or more locations for representations of objects that share a common description. The objects may include images and files. Note that the image is linked to and not embedded in the display. You can display an embedded image using the <dao> tag (see above).
In the example below the main <daodesc> description is used for the group and a description is given with the image (tiff file), to be used as the linking text. If you do not include a description or title, the URL will be used as the linking text.
<daogrp>
<daodesc><p>Digital representations of a letter</p></daodesc>
<daoloc href="http://host/digitalarchive/tiff/letter.tiff">
<daodesc><p>Digital scan of letter</p></daodesc>
</daoloc>
<daoloc href="http://host/digitalarchive/pdf/letter.pdf" title="PDF transcription"" />
<daoloc href="http://host/digitalarchive/msword/letter.doc" title="OCR of letter in MS Word format" />
</daogrp>