The CI_OnlineResource element is used in a variety of contexts in ISO19115 content. This complex-content-element provides a linkage to some online resource related to the metadata or the described context resource. It is thus analogous to atom:link (IETF RFC-4287) or the link element described in IETF RFC-5988.  For links that locate online documents accessible using standard browser and file type resolution technology, the link can be as simple as a single URL element that retrieves a representation of the resource. There are many other kinds of related resources that the onlineResource element may point to, including web services that provide access to a dataset resource, metadata for related or source resources, specifications for standards or extensions to standards. 

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Extracted text on CI_Online Resource from USGIN metatadata profile

FYI-- this is a draft profile against the upcoming revision of ISO19115 for metadata, scoped to energy industry, but the scope overlaps requirements for USGIN (I've been very active in developing profile and looked after that).  Please have a look at the docs if you're interested in metadata. Given the standards process time lines, it probably won't directly impact us until next year.

steve

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Following is a list of some metadata implementation recommendations and profiles I am looking at.