Data or Document? Migration of Descriptive Metadata for Medieval and Renaissance Manuscripts Between Data-Centric and Document-Centric Models: A Case Study

Data or Document? Migration of Descriptive Metadata for
Medieval and Renaissance Manuscripts Between Data-Centric and Document-Centric
Models: A Case Study

Elizabeth
J.
Shaw

Aziza Technology Associates
ejshaw@azizatech.com

2003

University of Georgia

Athens, Georgia

ACH/ALLC 2003

editor

Eric
Rochester

William
A.
Kretzschmar, Jr.

encoder

Sara
A.
Schmidt

This paper will discuss a case study of the dual direction migration of
metadata describing medieval and renaissance manuscript collections between
the Digital Scriptorium database schema and an XML DTD developed to encode
extant manuscript descriptions. This discussion highlights the challenges
and tensions that exist in trying to merge data that is captured in
different data models, roughly categorized as data-centric and
document-centric. The observations garnered from this study may have broader
implications for other efforts to meld distinct descriptive models for
unitary searching and resource discovery.

CONTEXT
The author was hired by Digital Scriptorium to:
1)provide XML —> HTML XSLT transformations of an electronic
version of the Huntington Library “Guide to Medieval and Renaissance
Manuscripts” which has been encoded in the TEI Medieval Manuscripts
Description Work Group (TEI MMSS) draft DTD ,
2) migrate data from the existing Digital Scriptorium database to
the the draft DTD and
3) migrate the TEI-MMSS encoded “Guide” to the Digital
Scriptorium’s existing database schema.
lIn the context of this work, many interesting challenges have come
to light.
The Digital Scriptorium database schema and the TEI MMSS draft DTD are
closely allied since some of the same people worked on both data models.
However, significant differences exist in nomenclature and structuring of
the data, both because the TEI MMSS DTD is an extension of TEI and because
the purpose of the TEI MMSS DTD is to allow for the capture of extant
descriptive information. The database schema, created prior to the DTD is a
more constrained data model and uses slightly different elements and
nomenclature for its basis.

DESCRIPTIVE TRADITIONS
Although the library community has largely settled on a particular
record-based model for descriptive information (the MARC record and AACR2)
about printed works, serials and selected media, many communities of
practice that have need of description to facilitate resource discovery and
scholarship have no such common standard. In many cases, a narrative form of
description has evolved in an attempt to capture the particular descriptive
needs of the curators and users of the materials. Descriptive practice in
disciplines such as manuscript collection or archives has varied greatly
across nations, institutions and within individual institutions over time.
This evolution has largely been dependent on the interests, energies and
capabilities of individual curators.
Furthermore, descriptive practice varies greatly between communities of
practice because of the particular characteristics of the disciplines that
they support. Both the elements of description fundamental to supporting
work and the nature of their expression may be unique. That these
descriptive needs vary greatly has become more obvious as efforts to develop
single metadata standards or standards that easily map across disciplines
have had limited success.
Nonetheless, these communities often face similar problems as they attempt to
migrate their formerly print based description to an electronic form that
can be shared across institutions. Each community must revalidate what
aspect of description is important to the work of the community, 2) define a
common way of expressing information about those important things and 3)
develop a model that accurately captures that information. The work must be
done in an environment with no uniform extant practice and differing
philosophies about the nature, scope and role of description in the
discipline. This paper will focus on two approaches to capturing significant
descriptive data within the same discipline and examine the challenges in
merging the two.

DATA-CENTRIC VS. DOCUMENT CENTRIC DATA MODELS
The numerous schemes for descriptive metadata that have emerged since the
advent of the web vary greatly in their scope, complexity and underlying
assumptions about the nature of descriptive practice. Ronald Bourret’s
article XML and Databases and his associated materials provide an
interesting framework from which to view these different approaches to
capturing descriptive metadata. The emerging practices might be categorized
into two distinct models:
Data-Centric models: These record-like
models capture discrete data elements in a structure that is well
represented in a flat or relational model (ie. Dublin Core, MARC).
Often these flat or relational representations atomize data at the
most discrete levels at which one might manipulate it. Some require
or enforce the normalization of the data, institute data typing and
constrain the syntactical expression in which it is represented. The
Digital Scriptorium database schema follows this record-like model,
though without some of the rigor of syntax that is required in a
MARC record.
Document-Centric models: These models
capture more narrative or discursive, often complex, hierarchical
descriptions. Often, they allow considerable flexibility in what
data elements are required, the form in which data is expressed, and
rarely (especially prior to the advent of XML Schema) utilize data
typing to constrain the expression of information.

These document-centric models may further be categorized as those that
provide a representation of an idealized model of descriptive practice and
those that represent extant descriptive practice. Those that attempt to
capture an electronic edition of an extant description are often the least
rigorous in their requirements for data elements and normalization because
of the need to accommodate heterogenous practice. The tension between
representing an idealized model of a particular document structure—either to
facilitate machine processing of the data or to enforce practice in a
community—and providing a model that captures existing representations has
been discussed extensively by authors such as Piez and in efforts to develop
data models such as the TEI dictionaries DTD

CAPTURING EXTANT DESCRIPTION
Although document-like descriptions from various institutions and time frames
seem similar in format they often contain distinctly different elements of
description in distinct orders and with variant nomenclature. This has
presented challenges to the developers of DTDs and schemas that attempt to
capture descriptive metadata in these communities of practice. DTDs such as
Encoded Archival Description (EAD) and the
TEI MMSS draft DTD are explicitly designed to accommodate a variety of
extant descriptive practice rather than constrain practice to the schema
developers’ prescribed notions of practice.
The extant documents that are encoded using these models often differ greatly
from their record-like cousins. Narrative and complex, they utilize indirect
reference, inference from context (the description of a manuscript written
in French may never explicitly state the language in which it is written,
assuming that the reader can discern from the quoted text imbedded in the
description), inference from relationships to siblings or parent elements,
and assumptions about relationships of the parts of the description that are
not explicit. Although a human reader can infer these relationships, the
lack of explicitness makes it more difficult to capture characteristics of
the described object in machine processable ways. To capture this
information explicitly requires modifying the extant description.
Data-centric models tend to capture this information in explicit ways from
the start.

MIGRATING DATA
Many practitioners and users of existing descriptive material find that even
when description is reworked by knowledgeable humans in order to import it
to a data-centric metadata representation, the records fail to capture
significant information that is embedded in the narrative of these extant
descriptions. In many cases, the original cataloger has specialized
knowledge of either the collection being described or of the field of study.
References to other significant or related work, connections between objects
in the collections are often lost in their transformation to data-centric
descriptions
Tensions between models for capturing descriptive metadata are often
amplified at the point at which migration occurs. Automated efforts to
migrate encoded extant description have met with mixed success. Chris Prom’s
migration of EAD encoded descriptions to Dublin Core RDF records for
importation into a cultural heritage OAI database points to some of the
problems inherent in automated migration of extant data. Lundberg discusses
the implications for information retrieval of data encoded in XML.

THE DIGITAL SCRIPTORIUM: CASE STUDY
This paper reports on the outcomes of the effort to automate the migration of
data captured in two distinct models and the resulting implications for
resource discovery. The paper describes:
the differing data models,
the process by which the migration occurred,
the challenges faced both in migration from relational database to
XML and in migration from XML to a relational database model,
the development of a relational database model that attempts to
capture both the XML encoded manuscript descriptions as well as the
data in the existing database
the trade-offs in these various representations and
the implications for information display and resource
discovery.

By highlighting points of ambiguity, strengths and weaknesses of the
different approaches to metadata capture and challenges in merging the data
into the same repository, it is hoped that this study will inform the work
of others who face similar challenges in their efforts to provide
descriptive metadata to their user communities.

REFERENCES

Ronald
Bourret

XML and Databases

Digital Scriptorum

Digital Scriptorium Database Schema

Encoded Archival Description

Sigfrid
Lundberg

Excursions along the border between metadata for
resource discovery and for resource description

Wendell
Piez

Beyond the ‘descriptive vs. procedural’
distinction

Extreme Markup Languages

Montreal, Canada

2001
197-214

Christopher
Prom

Does EAD play Well with Other Metadata Standards?:
Searching and Retrieving EAD using the OAI Protocols

Journal of Archival Organization

1
3

2003

(Forthcoming).

TEI dictionaries DTD

TEI Medieval Manuscripts Description Work Group (TEI
MMSS) draft DTD