1. Title
2. Subject
3. Description
4. Type
5. Source
6. Relation
7. Coverage
8. Creator
9. Publisher
10. Contributor
11. Rights
12. Date
13. Format
14. Identifier
15. Language
16. Audience
17. Provenance
18. Rights Holder
19. Instructional Method
20. Accrual Method
21. Accrual Periodicity
22. Accrual Policy

W3C Description (Content) Element: The description attribute provides a concise explanation of a Web page's content. This allows the Web page authors to give a more meaningful description for listings than might be displayed if the search engine was unable to automatically create its own description based on the page content.

Dublin Core Description Element: Description may include but is not limited to an abstract, a table of contents, a graphical representation, or a free-text account of the resource.

Description Element Notes: Since most visitors do not read past a first page with no scrolling.  Good advice is to prepare a sentence or two about the actual content of the page.  Like a book review short form.  What you include is really about visitor confidence.

 

W3C Title Element: Authors should use the TITLE element to identify the contents of a document. Since users often consult documents out of context, authors should provide context-rich titles.

Dublin Core Title Element: A name given to the resource. Typically, a Title will be a name by which the resource is formally known.

Title Element Notes: What is a meaningful or well structured title?  Trains or Electric Trains 1900-1950, In Europe?

Inappropriate titles are those which are only meaningful within context. Like introduction or my first web page.

W3C Keywords Element: Words that may be useful to search engines, and other data that is not considered document content. User agents do not generally render elements that appear in the HEAD as content. They may, however, make information in the head available to users through other mechanisms.

Dublin Core Keywords Element: Typically, the subject 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.

Keywords Element Notes: Why have keywords fallen into disrepute? Stuffing and unscrupulous web site authors.  Do they still serve a useful purpose?  Possibly, but especially if a glossary or a word map are present within the website.

W3C Language Element: Language information specified via the lang attribute may be used by a user agent to control rendering in a variety of ways. Some situations where author-supplied language information may be helpful include:
...Assisting search engines.
...Assisting speech synthesizers.
...Helping a user agent select glyph variants for high quality typography.
...Helping a user agent choose a set of quotation marks.
...Helping a user agent make decisions about hyphenation, ligatures, and spacing.
...Assisting spell checkers and grammar checkers.

Dublin Core Language Element: Used to designate a textual description of the content of the resource.

Language Element Notes: ISO 639 2 letter language codes. Suggested metadata related to language is below.

<meta name="language" content="en-US" />
<meta name="country" content="USA" />

W3C Memberships Element: The semantics of some of the elements are defined very broadly. An element may be repeated, to indicate multiple authors for example. The values of several elements may be taken from enumerated lists.

Dublin Core Memberships Element: Recommended practice is to include sufficient bibliographic detail to identify the resource as unambiguously as possible.

Memberships Element Notes: Organizations increasingly recognize the necessity to create and manage project entities like (meta-) models, document metadata, and classification ontology in such a manner that the integrative usage of these entities (called domain artifacts) is supported.

 

W3C Robots Element: When a Robot visits a Web site it checks for a robots text file to apply only to specific robots, and to disallow access to specific directories or files.

Dublin Core Robots Element: Access Rights may include information regarding access or restrictions based on privacy, security, or other policies.

Robots Element Notes: <meta name="robots" content="ALL" /> would permit robots (spiders, spidering) full access to a web presence where included.

Valid reasons exist for excluding robots from harvesting information from your web presence.  However careful consideration should be given.  When contemplating a blanket exclusion for all web pages or sources.