Dublin Core - the topic of the resource. Typically, the topic will be represented using keywords, key phrases, or classification codes. Recommended best practice is to use a controlled vocabulary. To describe the spatial or temporal topic of the resource, use the Coverage element.
- NSDL usage - the topic area, focus, theme or content matter of a resource
- Field usage - strongly recommend
- Number of occurrences - repeat the field as necessary
A specific NSDL controlled vocabulary is not used because:
- the NSDL has grown beyond the ability of a simple, single vocabulary list being capable of effectively describing the entire scope of the library
- many contributors (including Pathways) use subject-oriented vocabularies specific to their audiences and combining such lists into a NSDL supported controlled vocabulary is not practical in terms of scale or organization of such a list
- resources are not available to formulate and maintain a subject list (if a list is deemed practicable) that would encompass the NSDL scope
Rather use the following recommendations for creating metadata for the subject field:
- Use keywords or short phrases extensively
- Pathways and other contributors continue to use existing controlled vocabularies (e.g. Library of Congress)
- Pathways and other contributors continue to use their own controlled vocabularies. Terms from some Pathway vocabularies are below.
The controlled vocabularies of Pathways and other contributors are treated as free-text keywords within the subject field. That is, a method does not exist in the XML of the NSDL_DC metadata framework to indicate that a Pathway or other controlled vocabulary is being used.
Cataloging best practices
- Include terms that describe the predominant content of the resource.
- Include terms that describe the resource in the context of science, technology, engineering and mathematics education and research.
- Choose significant and unique words.
- Avoid words that are too general to describe a particular item.
- Provide sufficient terms to facilitate discovery.
- Do not repeat variations of terms, synonyms, case or tense variations or alternate spellings.
Use and resource examples
XML tips and examples
- When using local vocabulary terms, do not use the any refinement in XML documents.
<dc:subject xsi:type="dct:LCC">Agriculture</dc:subject> this is not XML schema enforced for LCC
<dc:subject xsi:type="dct:LCC">Animal culture </dc:subject> this is not XML schema enforced for LCC
<dc:subject>put any keyword here</dc:subject>
<dc:subject>or keyword phase</dc:subject>