Here's my understanding of the relationship between EAD and RDF; what
follows is a great simplification. Clarification and amplification is very
1. At a very general level, EAD and RDF are both about metadata. The
relationship doesn't go much beyond that as they each occupy a different
part of the descriptive standards firmament.
2. EAD is an instance of an SGML Document Type Defintion. RDF is a syntax
for expressing metadata schemas. To fully appreciate the difference, one
must understand the difference between a DTD and a schema. (The following
statements may be treading on thin ice.) DTDs are an SGML technique for
defining the structure and meaning of the data in a class of documents.
They are fundamental to all SGML documents and may apply to XML instances as
well (must apply if the instance is valid rather than simply "well-formed".)
Schemas are an XML device that parrallels and extends the concept of the DTD
by permitting the specification of additional characteristics of the data
elements- beyond those that a DTD can define. For example, the data type of
the element- integer, date, etc.- characteritics common in specifications in
the database world. RDF is a specification for the building of a
particular class of schemas- those relating to metadata. There is no
direct parallel in the world of DTDs.
3. The following table (which probably needs refinement and clarification)
attempts to put them in their relative postion in the standards hierarchy.
Apologies to all whose mail reader cannot digest my formatting.
SGML DTD syntax Schema syntax
RDF- a schema syntax for metadata
Particular DTDs (e.g. EAD) Particular schemas expressed in RDF
4. If my formatting persists in your mail reader, you can see that EAD and
RDF do not appear in the same position in this standards hierarchy.
5. Of course, to my knowledge no one has actually expressed EAD in an RDF
schema format but I suspect that it can be done.
6. One could, I believe, convey an EAD instance as an RFD instance using
the XML namespace concept.
Such an instance might look like this.
The namespace declaration in the first line undoubtedly needs to be
modified, but you get the idea. The namespace declaration EAD that preceeds
each EAD element in the start and end tags is there to distinguish the
syntactical source of the element and distinguish it from elements defined
by other syntaxes such as Dublin Core, HTML, etc. especially those with
identical element names.
7. While the above is valid, I'm not sure if an RDF-aware processor can
actually make use of this instance without reference to an EAD RDF schema.
Does anyone know if there are any RDF-aware processors in use?
8. There is a major fundamental difference in the way EAD instances are
meant to work and the manner in which RDF is envisioned to operate. An EAD
instance is metadata that resides independantly on the Web as a pointer to
another entity, the archival materials that it describes. Like a catalog
record that points to a collection somewhere else, say in the stacks.
RDF is used to express metadata that is carried with the object it
describes. Like Cataloging in Publication data that appears in the front of
9. For archives that are using XSL to transform their EAD instances to
HTML for browser display, there is another option for embedding metadata
that browsers and Web search engines can read. That is the embedding of a
set of metadata about the collection in a syntax such as Dublin Core that
the generalized search engines behine Yahoo, AltaVista, etc. can read.
These may be embedded in <meta> elements in the htiml <head>
Head of Processing
Minnesota Historical Society
345 Kellogg Blvd West
St. Paul MN 55102-1906
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**NOTE NEW AREA CODE EFFECTIVE JULY 12, 1998**
> From: Tone Merete Bruvik[SMTP:[log in to unmask]]
> Sent: Tuesday, May 25, 1999 8:09 AM
> To: Multiple recipients of list EAD
> Subject: RDF metadata and EAD
> We have got questions about the relationship between EAD and general
> metadata description systems, as Resource Description Framework - RDF.
> RDF is a "declarative language and provides a standard way for using XML
> represent metadata in the form of properties and relationships of items on
> the Web." (quote from http://www.w3.org/Metadata/Activity.html). I can see
> that RDF can be used to express the metadata about a XML or HTML resource,
> but when we are working with archival materials, as we do when using EAD,
> all our data is metadata, but not the same kind of metadata as the
> about the finding aid. Some of our coop partners ask if RDF might be an
> alternative to EAD, but we think that RDF is covering something different
> than EAD. Our knowledge to EAD is good, but RDF is new to us, so if anyone
> have comments on this it would be most welcome.
> Thanks for any comments or suggestions.
> Tone Merete
> Tone Merete Bruvik Tel: +47 55 58 42 22
> [log in to unmask] Fax: +47 55 58 94 70
> HIT - Humanities Information Technologies Research Programme
> University of Bergen, Allégt. 27, N-5007 BERGEN, Norway