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Overview of Topic

When the world ventured into digital age, the quantity and complexity of electronic

resources expanded exponentially due to the rise of new technologies. As a result, the number of

digital libraries grew in an attempt to organize, manage, and provide access to these resources,

which lead to metadata becoming a central component in data management. To provide quality

metadata, these libraries required a structured framework. Thus, a vast variety of metadata

schemes emerged as methods to gain bibliographic control over these types of resources. Since

there are a multitude of metadata standards with different purposes and audiences, this essay will

focus on the most prevalent general-purpose metadata schemes for information resources in

digital libraries: Dublin Core (DC), Metadata Object Description Schema (MODS), and

Metadata Encoding and Transmission Standard (METS).

Dublin Core Article Summary

This article provides an overview of DC’s purpose, levels of use, and practical

recommendations for creating effectual metadata. According to the author, DC is an international

standard for descriptive metadata that is designed as an inexpensive and less complex substitute

for MARC. DC has two types, which are simple and qualified. Simple DC only utilizes the first

15 elements while the qualified DC includes additional elements along with the option to add

refinements to the original elements. Since simple DC can hinder resource discovery due to its

incompleteness, this article focuses on the qualified version of DC. The author lists some useful

guidelines to ensure the success of information retrieval such as the completeness and

consistency of descriptions. After the overview of the metadata standard, each of the elements is

thoroughly examined and the instructions for their use are provided. Coleman (2012) breaks

down the explanation of the elements into the following method of organization: “Name, Label,

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Definitions, Comments, Chief Source of Information, Controlled Values, Inputting Guidelines

and Notes” (p. 158).

Metadata Object Description Schema Article Summary

This paper gives a quick intro to MODS and outlines its essential guiding principles and

features. MODS is a schema for descriptive metadata based off of MARC21. It manages to

utilize the XML format while maintaining its compatibility with MARC21. The author

emphasizes that MODS is designed to be a simple and efficient alterative to MARC especially

for electronic resources. As part of its aim for simplicity, MODS uses language-based tags, less

coded values and combines fields from MARC into one MODS element for several tags.

Furthermore, McCallum (2004) highlights the “advantages of XML and the flexibility, tool

development, and transformation options it offers” (p. 88). Some examples of these advantages

include its linking attributes, element-level language attributes, and its hierarchical structure.

Metadata Encoding and Transmission Standard Article Summary

This article provides a brief introduction to METS by providing its definition, function,

and goals. Cantara (2012) succinctly defines METS as a “data communication standard for

encoding descriptive, administrative, and structural metadata regarding objects within a digital

library, expressed using the XML Schema” (p. 237). The METS framework attaches all forms of

metadata to digital objects so that it can effectively manage and exchange them throughout

digital repositories. Through this function, the author asserts that METS is able to achieve

interoperability, scalability, and digital preservation.

In the second section of the paper, the structure and components of METS are described

along with a basic foundation for application. The article explores the six optional sections of a

METS file, which are comprised of a header, descriptive metadata, administrative metadata,

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behavior metadata, file inventory, and structural map linking in addition to the one required

component, the structural map. The role and usage of each component in the document are

discussed and the major elements, sub-elements, and attributes for every section are explained.

Comparative Analysis of DC, MODS, METS

Despite the different ways these articles analyze metadata schemes, they all examine the

objectives, functions and structure of the frameworks because the authors recognize that these

are the essential properties which construct a metadata standard. Therefore, this essay will

compare these schemes based on those same foundations. By comparing the functions, objectives

and structure of DC, MODS and METS, the advantages and disadvantages of each framework

will become apparent.

The functions of DC, MODS, and METS are varied, but have some commonalities. The

prevalent unifying function of these metadata schemes are that they are primarily designed to aid

in information retrieval, data exchange, and accelerate the cataloging of information resources in

digital libraries. Apart from these broad shared aims, DC and MODS have a more specific

function, which is to provide medium to describe bibliographic information while the primary

purpose of METS is to attach all forms of metadata to digital objects and store or share them in

digital libraries.

Although the functions of these metadata schemes have a measure of incongruity, they all

share the same objectives, which are to increase the simplicity and flexibility of record

descriptions as well as to improve the interoperability of the record’s between library systems.

Compared to extensive 999 fields of MARC and the complexity of its rules, these frameworks

range from exceedingly simple to moderately simple. DC, MODS and METS’s non-numeric

elements and absence of rigid input requirements contribute to their accessibility. DC’s highly

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adaptable resource description and the various features of XML utilized in MODS and METS

give these standards a great deal of flexibility, albeit in different ways. Just as XML promotes

flexibility, it also improves interoperability for MODS and METS. Since DC serves an

international community, it offers some interoperability as well, but not on the same scale as

MODS and METS.

These objectives ultimately contribute to the structural form of these metadata formats in

terms of the extensity of elements, types of organizational structure and encoding methods.

Qualified DC is comprised of 16 top-level elements whereas MODS contains 19 top-level

elements. For both DC and MODS, all these elements are optional and repeatable. Also, each

element for these schemas can be refined using qualifiers and attributes. Since MODS has

additional elements and attributes to refine its records and create more comprehensive records, it

offers a higher degree of description and granularity than DC does. Furthermore, DC’s structure

lacks the ability to show relationships between its elements in contrast to MODS, which is

hierarchical in nature. To some extent, the structural design of MODS is modeled after

Functional Requirements for Bibliographic Records (FRBR). McCallum points out in her article

that each top-element in MODS falls into the work, expression and manifestation categories of

FRBR. This framework is able to exploit the hierarchal organization of the XML syntax by

showing the relationship between items and the hierarchies of the record’s descriptions. In

comparison, METS also has a hierarchical structure, but not in the same way as MODS. One

prevalent example of this hierarchy is the structural map element of METS because it allows the

content of a digital object to be displayed hierarchically through the use of the XML nested

divisions, which shows the relationship among the different file components.

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When comparing METS to DC and MODS, it is important to take into account that the

function and structure of METS differs drastically from the other schemes. Therefore, aside from

generalities, METS cannot structurally be compared with DC and MODS because it is not solely

a descriptive metadata format like the others. METS is an extremely structured and modular

framework for all kinds of metadata that features some unique characteristics, which set it apart

from DC and MODS. For instance, METS is able to link or incorporate other metadata schemes

into the METS document including DC and MODS in the descriptive metadata section.

Additionally, the behavior section of a METS file has the capacity to contain executable scripts

like page-turning or multimedia applications. These added features give METS power and utility

that descriptive metadata on its own is lacking.

Conclusion

After a side-by-side examination of these frameworks, it is clear that they offer certain

conveniences that MARC does not, but these advantages can contribute to problems that affect

their efficiency. DC’s simplicity adversely affects its functionality because it increases the

chance of producing vague and misleading descriptions. The structural design of MODS causes

reciprocal MARC conversion issues, resulting in loss of data. The versatility of METS has the

potential to create interoperability complications because it allows the option for metadata to be

stored internally or externally and permits the use of any extension scheme. Ultimately, these

disadvantages of the metadata schemes arise from the difficulties of practically applying their

principles within the confines of the structure and encoding format. An ideal standard would

achieve balance among simplicity, flexibility and interoperability while retaining functionality

and modularity.

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References

Cantara, L. (2012). METS: The Metadata Encoding and Transmission Standard. In R.

Smiraglia (Ed.), Metadata: A cataloger's primer (pp. 237-253). Hoboken: Taylor and Francis.

Retrieved from: http://usf.eblib.com.ezproxy.lib.usf.edu/patron/FullRecord.aspx?p=1074572

Coleman, A. S. (2012). From Cataloging to Metadata: Dublin Core Records for the

Library Catalog. In R. Smiraglia (Ed.), Metadata: A cataloger's primer (pp. 153-181). Hoboken:

Taylor and Francis. Retrieved from:

http://usf.eblib.com.ezproxy.lib.usf.edu/patron/FullRecord.aspx?p=1074572

McCallum, S.H. (2004). An introduction to the Metadata Object Description Schema

(MODS). Library Hi Tech, 22(1). 82-88. Retrieved from

http://dx.doi.org.ezproxy.lib.usf.edu/10.1108/07378830410524521

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Photocopies of the Articles

DC and METS Articles - https://drive.google.com/file/d/0B--

7pAmG9nEccG9vQU51OVF2eDQ/edit?usp=sharing

MODS Article - https://drive.google.com/file/d/0B--7pAmG9nEccG5JX09yVGNsd1k/edit?

usp=sharing

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