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Referent (rft)

The Referent is what an OpenURL is about: the resource being requested. It is the only required entity in a ContextObject.

The Referent is the resource being referenced — the article, book, chapter, dissertation, or patent that the user is trying to reach. Every ContextObject contains exactly one Referent; the rest of the entities supply context around it. In KEV form, the Referent's descriptors are prefixed rft.

Ways to describe a Referent

A Referent may be described by any combination of an identifier, By-Value metadata and By-Reference metadata (a fourth Descriptor, Private Data in rft_dat, depends on a prior agreement with the resolver and is discouraged):

By metadata (By-Value)

Descriptive bibliographic metadata is sent inline. The format used is named by rft_val_fmt:

rft_val_fmt=info:ofi/fmt:kev:mtx:journal
&rft.atitle=An+Article+Title
&rft.jtitle=A+Journal+Title
&rft.date=2020
&rft.volume=10
&rft.spage=1

Which descriptors are valid depends on the named format. See the format reference pages: journal, book, dissertation, patent.

By identifier

A URI identifier for the Referent is sent in rft_id:

rft_id=info:doi/10.1103/PhysRev.47.777

The identifier may appear without any descriptive metadata, provided the resolver knows the namespace. See Identifiers for the registered forms.

By reference

The metadata describing the Referent is stored elsewhere; the OpenURL points to it:

rft_ref_fmt=info:ofi/fmt:xml:xsd:journal
&rft_ref=https://source.example.com/contextobjects/12345.xml

The resolver fetches the referenced metadata record (here a Journal XML record) and parses it. rft_ref_fmt and rft_ref must be used together. This is different from the By-Reference transport, which points at a whole ContextObject; see Transports.

Combining methods

The methods can be combined. It is common to include both a DOI and a complete set of descriptive metadata, so that a resolver can use the DOI when its knowledge base recognises it and fall back to metadata when it does not:

rft_val_fmt=info:ofi/fmt:kev:mtx:journal
&rft_id=info:doi/10.1103/PhysRev.47.777
&rft.atitle=Can+Quantum-Mechanical+Description+of+Physical+Reality+Be+Considered+Complete%3F
&rft.jtitle=Physical+Review
&rft.aulast=Einstein
&rft.date=1935
&rft.volume=47
&rft.spage=777

The genre key

The journal and book formats define a rft.genre key that names the kind of item. Journal: journal, issue, article, proceeding, conference, preprint, unknown. Book: book, bookitem, conference, proceeding, report, document, unknown. The dissertation and patent formats have no genre key; the format itself says what the item is. Sending rft.genre helps a resolver when the rest of the metadata is thin.