Dublin Core Metadata Initiative

The best known metadata intiative on the Web, the Dublin Core began in 1995 at a workshop in Dublin, Ohio, and has been revised a few times since then. The current version of the DCMI element set has 16 base elements (which use a “DC” prefix when used in meta elements) and 30 qualified elements (which are more specific versions of the base tags, and which should begin with the “DCTERMS” prefix; see below for information about older versions of Dublin Core).

Dublin Core is noteworthy among metadata schemes in that it also includes a set of predefined “encoding schemes” that can be used in the scheme attribute of a meta element. Officially-recognized Dublin Core encoding schemes also use a “DCTERMS” prefix. For example, these two tags use the W3CDTF scheme, which indicates the dates are encoded using the same format used by the WorldWide Web Consortium:

<meta name="DC.date" content="2000-01-01" scheme="DCTERMS.W3CDTF">
<meta name="DCTERMS.created" content="2001-01-01" scheme="DCTERMS.W3CDTF">

(Earlier drafts of the Dublin Core standard encouraged concatenating qualifiers onto their unqualified equivilents. (For example, name=”DC.date.created” instead of name=”DCTERMS.created”.) They also allowed page authors to create custom qualifiers, but the current versions of Dublin Core allow only the 46 official values, because custom values aren’t easily converted to other formats like XML, and often don’t “dumb down” (correlate with unqualified elements) well.)

If the content of a Dublin Core element is a URI, the element may be better expressed as a link element.

Reference: Expressing Dublin Core in HTML/XHTML meta and link elements

Example:

<meta name=”DC.title” content=”SEO Company | Providing Best Internet Marketing &amp; SEO Services” />
<meta name=”DC.description” content=”MarketRaise is a serious SEO company providing the best results for the best rates regarding any Internet Marketing and SEO Services.” />
<meta name=”DC.date” content=”2005-03-24″ />
<meta name=”DC.format” content=”text/html” />
<meta name=”DC.contributor” content=”SEO Company with Internet Makrketing Initiative” />
<meta name=”DC.language” content=”en” />