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Guidelines

The Nanopublication Guidelines specify the minimal formal structure of a nanopublication, and the Nanopublication Schema defines its vocabulary in RDF. This page summarizes them.

Structure​

A nanopublication is a set of RDF quads in four named graphs:

  • The assertion graph holds the main content.
  • The provenance graph says how the assertion came to be, and must refer to the assertion graph.
  • The publication info graph has metadata about the nanopublication as a whole, such as its creator and creation time, and must refer to the nanopublication.
  • The head graph ties the three together and identifies the nanopublication.

This is a minimal nanopublication in TriG, the recommended syntax:

@prefix : <http://example.org/pub1/> .
@prefix ex: <http://example.org/> .
@prefix np: <http://www.nanopub.org/nschema#> .
@prefix prov: <http://www.w3.org/ns/prov#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix dct: <http://purl.org/dc/terms/> .
@prefix orcid: <https://orcid.org/> .

:Head {
  : a np:Nanopublication .
  : np:hasAssertion :assertion .
  : np:hasProvenance :provenance .
  : np:hasPublicationInfo :pubinfo .
}

:assertion {
  ex:trastuzumab ex:is-indicated-for ex:breast-cancer .
}

:provenance {
  :assertion prov:wasDerivedFrom :experiment .
  :assertion prov:wasAttributedTo orcid:0000-0003-3934-0072 .
}

:pubinfo {
  : dct:creator orcid:0000-0003-0183-6910 .
  : dct:created "2020-07-10T10:20:22.382+02:00"^^xsd:dateTime .
}

Well-formed nanopublications​

A nanopublication is well-formed if:

  • every triple is in one of the four graphs, and every graph has a URI;
  • the head graph contains exactly one rdf:type np:Nanopublication triple, which identifies the nanopublication URI;
  • the head graph links the nanopublication to exactly one assertion, one provenance, and one publication info graph;
  • the URIs of the nanopublication and its four graphs are all different;
  • the provenance graph refers to the assertion graph at least once, and the publication info graph refers to the nanopublication at least once.

Identifiers​

Nanopublications are immutable, and their identifiers make this checkable. The recommended way is a Trusty URI: a URI that ends in a cryptographic hash of the nanopublication's content, like RAlohixCBW... in this example. Anyone who has the content can recompute the hash and check that it matches. The URIs of the graphs and of other resources the nanopublication defines are derived from its URI, so they are fixed by the hash too.

Signatures​

In the current ecosystem, nanopublications are also signed. The publication info graph then contains the creator's public key and a signature, and the trusty URI is computed over the signed content. The quick start shows how to sign, verify, and publish nanopublications.

Learn more​

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