Naming and Discovery Services

Annotea. Annotea is based on RDF specifications and it identifies resources through URIs. URIs point the whole document while an additional property, context, contains an Xpointer [50] expression for a fine-grained addressing within the content annotated. For example, if one annotates a math expression in MathML in the third paragraph of an XHTML page, the URI would point the Web page, while the context property contains the information to locate the expression in the third paragraph in the main body of the page.

SAM. SAM and CMCS use the URL to identify a resource and its associated metadata. Any access to or modifications of the metadata must be using the same URL with appropriate function calls to distinguish between the resource and the metadata.

IKM. IKM assigns IDs to each multimedia resource, and retrieves and relate the resources through these IDs.