The research leading to these results has received support from the
Innovative Medicines Initiative (IMI)
Joint Undertaking under grant agreement n° 115191, resources of which
are composed of financial contribution from the European Union's
Seventh Framework Programme (FP7/2007-2013) and EFPIA companies’ in
This dataset and linkset description specification is intended for data providers who want to publish their data as RDF, and link it to other datasets. A basic knowledge of RDF is assumed.
Details for converting a dataset and publishing it as RDF are given in the Open PHACTS RDF guidelines specification [[OPS-RDF]].
The Open PHACTS platform [[OPS-ARCH]] relies on data and the interlinks published by a variety of sources. For example, details of chemicals are derived from ChemSpider, ChEMBL, and DrugBank. This specification provides details of the metadata expected to describe the datasets and the links that relate the instances in those datasets.
The Open PHACTS project has produced a set of guidelines aimed at data providers for publishing their data within the OPS system [[!OPS-RDF]]. The RDF guide provides details about modelling your data as RDF. This specification builds on the RDF Guidelines by defining the metadata that should be published to describe the dataset and the links to other datasets.
The dataset description defined in this specification declares the properties that should be included in the description of dataset or its links. The information is exchanged using the Vocabulary of Interlinked Datasets [[VOID]]. The VoID Editor can be used to create dataset descriptions, although in general they should be generated as part of the data creation pipeline.
All examples in this document are written in the Turtle RDF syntax [[TURTLE]]. Throughout the document, the following namespaces are used:
@prefix dcterms: <http://purl.org/dc/terms/> . @prefix dul: <http://www.ontologydesignpatterns.org/ont/dul/DUL.owl#> . @prefix foaf: <http://xmlns.com/foaf/0.1/> . @prefix freq: <http://purl.org/cld/freq/> . @prefix owl: <http://www.w3.org/2002/07/owl#> . @prefix pav: <http://purl.org/pav/> . @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> . @prefix skos: <http://www.w3.org/2004/02/skos/core#> . @prefix voag: <http://voag.linkedmodel.org/schema/voag#> . @prefix void: <http://rdfs.org/ns/void#> . @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
Furthermore, we assume that the empty prefix is bound to the base URL of the current file like this:
@prefix : <#> .
This allows us to quickly mint new identifiers in the local namespace.
In this section, we introduce the vocabularies that will be used for capturing the dataset descriptions and the mappings between the datasets.
The Vocabulary of Interlinked Datasets (VoID) [[!VOID]] is a W3C interest group note that specifies a vocabulary for describing the metadata about a dataset and its relationship with other datasets. The vocabulary builds upon existing metadata vocabularies, e.g. Dublin Core Terms [[DCTERMS]], and captures four categories of metadata:
The VoID specification [[VOID]] defines a dataset to be, "a set of RDF triples that are published, maintained or aggregated by a single provider." The dataset itself may contain logical subsets, which can be captured in the VoID description of the dataset, e.g. ChEMBL can be split into subsets for compounds, targets, etc.
The information captured about a dataset focuses on the general metadata, access, metadata, and the structural metadata.
The VoID specification [[VOID]] defines a link to be, "an RDF triple whose subject and object are described in different datasets." The links capture the mapping of an identifier in one dataset to be related to an identifier in another dataset. VoID is agnostic to the relationship to use: possible predicates are given in the next section.
The VoID specification defines a linkset to be, "a collection of such RDF links between two datasets." The linkset captures details of the links, i.e. the datasets that are linked and the relationship, as well as the metadata associated with the links, e.g. provenance information about who created the mapping and the specific versions of the datasets related. The VoID specification enables a separation between (1) the datasets involved in a linkset, and (2) who publishes the linkset.
Note that a VoID linkset is defined to link two datasets via
a single link predicate
As such, there can
exist multiple linksets relating the same pair of datasets, as
illustrated in the figure below. The
figure depicts four distinct linksets: two sourced from ChemSpider
depicted in blue which use different link predicates; one sourced
from ChEMBL depicted in red; and one sourced from a third party
depicted in green. Each of the linksets uses a different link
relationship. Those shown with a double arrow head are symmetric
while those with just a single arrow are directional links.
A mapping is expressed as a VoID link, i.e. it is an RDF triple that relates an identifier in one dataset with an identifier in another dataset with some predicate which provides the meaning of the mapping. A justification for the mapping, e.g. two chemical compounds are deemed equivalent as they have the same InChI key, is expressed with the link in the linkset metadata.
The mapping predicate captures the way in which the two
identifiers are related. The mapping should respect the
semantics of the relationship, e.g. the
relationship must only be used when the two identifiers are
Standard, and widely used, generic mapping relationships are given in the table below. (A fuller mapping ontology is given in [[Halpin2010]], but it is expected that the main relationships used will be those given in the table.)
||General link, that indicates that the resource linked to is relevant to the subject. See http://www.w3.org/TR/rdf-schema/#ch_seealso.|
||This link indicates that the linked resources are in some way associated. See http://www.w3.org/TR/skos-reference/#mapping.||Symmetric|
||This link indicates that the linked resources are the same, under some assumptions or applications. See http://www.w3.org/TR/skos-reference/#mapping.||Symmetric|
||This link indicates that the linked resources are the same, under the assumptions of most applications. See http://www.w3.org/TR/skos-reference/#mapping.||Transitive Symmetric|
||This link indicates that the linked resources are the same under all assumptions and can be used interchangeably. Note that if this link is used for classes, then reasoning tasks will fall under OWL Full semantics. See http://www.w3.org/TR/2009/REC-owl2-quick-reference-20091027/#Axioms.||Transitive Symmetric|
||This link indicates that the linked resources (which are both classes in some ontology) are the same. See http://www.w3.org/TR/2009/REC-owl2-quick-reference-20091027/#Axioms.||Transitive Symmetric|
Note that there are domain specific relationship that may also be
used to express the relationship between two data instances. For
example, ChEBI provides a set of relationships including for
A key feature of the Open PHACTS platform is its ability to allow multiple views of the linked data which is achieved by applying scientific lenses over the data [[OPS-LENSES]]. For example, when performing an early stage exploratory task it is desirable to retrieve as much data as possible and as such the system enables the use of a lens whereby compounds are matched on their structural skeleton. Once the research has progressed further, the need for stricter relationships becomes apparent and the structure lens is switched for one which matches compounds on their full chemical structure, i.e. including their charges and stereo-chemistry.
The ability to classify linksets for use under different scientific lenses relies on the justification given in the linkset. A set of vocabulary terms for providing justifications are given in Appendix A.3.
The following example declares that the ChemSpider α-Ketoisovaleric acid concept with the CSID 48 shares many properties with the ChEMBL 3-Methyl-2-oxobutanoic acid concept with the ChEMBL-RDF ChEMBL ID CHEMBL146554. The relationship is drawn from ChemSpider based on the compounds sharing the same structure based on their InChI Keys (in this case the compound has the same InChI Key QHKABHOOEWYVLI-UHFFFAOYSA-N in both data sets.). Only the triples directly related to declaring the link are given in the example.
@prefix chembl: <http://linkedchemistry.info/chembl/chemblid/> . :cs2chembl_inchi void:linkPredicate skos:exactMatch . :cs2chembl_inchi dul:expresses <http://semanticscience.org/resource/CHEMINF_000059> . <http://rdf.chemspider.com/48> skos:exactMatch chembl:CHEMBL146554 .
We assume that an RDF representation of the dataset has been generated according to the Open PHACTS RDF Guidelines [[OPS-RDF]]. This section describes the information that must appear in the VoID description for the dataset.
It is recommended that the generation of the VoID description for a dataset is carried out as part of the creation of the RDF version of the dataset. To help understand some of the principles of the VoID description, that is to help you get started there is a VoID Generator which supports the creation of dataset descriptions.
For more details see Section 1.3 of the VoID Specification.
For more details see Section 2.2 of the VoID Specification.
For more details see Section 2.2 of the VoID Specification.
An example of an external page that may be linked is the bioDBcore [[BioDBcore]] entry, see Section 7.2.
For more details see Section 2.1 of the VoID Specification.
Where possible, we recommend publishing data under an open license to enable reuse of the data with appropriate acknowledgement. For Open PHACTS, the recommended license is CC-BY-SA. A list of alternative licenses are available in Section 2.4 of the W3C note on VoID.
For more details see Section 2.4 of the VoID Specification.
Note that the object of the
is a literal, not a URI.
For more details see Section 4.2 of the VoID Specification.
pav:versionpredicate, where this exists for the dataset.
Not all dataset have the notion of a version number. Where the dataset does have this notion, it must be given in the description. For other datasets, the versioning information will be inferred by the last modified date provided as part of the provenance information.
Details of the origin of the data must be provided using one of the following groups of predicates.
dcterms:publisherto capture who published the data.
dcterms:createdto capture when the dataset was created.
dcterms:modifiedto capture when the last update was made.
dcterms:modifiedto be declared. This ensures that we know which version of the dataset has been used.
Note that the object of the
pav:xxxBy predicate is
We currently do not require a specific form of URI for capturing the details of a person or entity. Future versions of this specification may recommend the use of ORCID Identifiers [[ORCID]].
Metadata that is common between the subsets can be declared for the parent only. However, the subsets allow for more specific linking between datasets and for providing details of the subject.
In the VoID note [[VOID]], the
is used for both subset of and has subset. The
declared semantics for the property is has subset. Within
Open PHACTS, the property must be used with the has subset
For more details see Section 4.4 of the VoID Specification.
For more details see Section 4.3 of the VoID Specification.
Multiple topics can be declared. If the data is split into subsets, then the topics should be associated with the subsets. BioPortal [[BioPortalWeb]] [[BioPortal]] can be used to search for suitable vocabulary terms for topics. DBPedia URIs may also be used. A list of common terms relevant for Open PHACTS is given in Appendix A.1.
For more details see Section 2.5 of the VoID Specification.
Multiple resources can be declared. If the data is split into subsets, then the example resources should be associated with the subsets.
For more details see Section 4.1 of the VoID Specification.
For more details see Section 3.3 of the VoID Specification.
For more details see Section 3.2 of the VoID Specification.
voag:frequencyOfChangepredicate together with a frequency term drawn from the Frequency Vocabulary.
The terms from the Frequency Vocabulary have been reproduced in Appendix A.2.
Other metadata that can be associated with a dataset may be included, see the VoID specification [[VOID]] for additional properties that may be incorporated. The dataset may also have a provenance graph associated with it providing more detailed information about the creation, authorship, and derivation of the dataset. This provenance graph should be expressed using the W3C Provenance Ontology [[PROV-O]].
Example VoID dataset descriptions can be found in Appendix B. The first example is for the ChemSpider dataset (see Appendix B.1). Note this example is derived from the existing non-conformant ChemSpider VoID description available from http://rdf.chemspider.com/void.rdf.
The second example is for the RDF representation of the ChEMBL database, given in Appendix B.2. This demonstrates the level of information required to track the provenance from a source dataset through to the RDF representation. It also contains subset definitions.
The two preceeding sections have prescribed the metadata required to describe datasets and the linksets that inter-relate them. This section outlines the expected deployment and exchange mechanisms and should be read in conjunction with Section 6 of the VoID specification for more details.
VoID documents describing datasets and linksets must contain a metadata block describing the VoID document using the following properties:
Of course, other properties may also be declared, e.g. a title using
dcterms:title. For more details, see
Section 6.2 of
the VoID specification [[VOID]].
An example is given below for the ChemSpider deployment. Note the use of an empty-string relative URI (<>) as a syntactic shortcut for the URI of the document that contains the statements.
<> a void:DatasetDescription ; dcterms:title "ChemSpider VoID Description"^^xsd:string ; pav:createdBy <http://www.chemspider.com/> ; pav:createdOn "2012-05-02T13:50:34Z"^^xsd:dateTime; pav:lastUpdateOn "2012-08-10T13:52:12Z"^^xsd:dateTime; foaf:primaryTopic :chemSpiderDataset .
Several mechanisms for deploying VoID descriptions are given in Section 6 of the VoID Note [[VOID]].
For datasets that are being published in their own domain, with
dereferenceable URIs, then we recommend placing the dataset's
VoID description in the root directory in a file called
void.ttl, with a local "hash URI" for the dataset
(and any subsets). For example, for ChemSpider we would have a
URI such as
When the code is being hosted on an external service, then the
VoID descriptor should be provided in the dataset's home
directory. For example, for the RDF encoding of ChEMBL this
Examples of the VoID descriptors are given in
Each RDF document containing the data should then contain a backlink to the dataset descriptor. For example, the ChEMBL-RDF molecule m1, there would be the triple:
<http://linkedchemistry.info/chembl/chemblid/molecule/m1> void:inDataset <http://linkedchemistry.info/chembl/chemblid/void.ttl#chembl-rdf_compounds> .
Tooling being developed within Open PHACTS should support the
predicates stated in this document. However, they should also be
able to read VoID files from external sources that do not comply
completely with this specification, but do comply with the VoID
standard [[VOID]]. An example would be the use of the
void:target predicate instead of the
void:objectsTarget predicates. Such usage should
not be the norm and should result in warnings being generated.
Nanopublications [[NANOPUB]] provide a means for data providers to obtain credit for their data contribution, in particular data that can be described in the form of a minimal set of assertions: a minimal piece of information that represents value for which credit is due. Such information is closely related to a link relating instances in two datasets. In some cases it may be desirable to publish a link as a nanopublication. This should not violate a link being published in a linkset according to this specification.
BioDBcore defines the following properties as the set of metadata that should be published in relation to a dataset. The aim of BioDBcore is different from that of VoID, but many of the elements defined are covered in the Open PHACTS dataset description.
An example BioDBcore record for ChEMBL.
The metadata specified in Section 4 covers the functional data required from BioDBcore. The aspects not covered are those relating to discovering who is responsible for a dataset and the publications about the dataset. It is expected that such information can be discovered from the dataset's homepage and is not within the use case scope for the description of the dataset. Such information may be added as additional statements in the VoID description.
There are a wide range of provenance vocabularies that have been proposed. This section gives brief pointers to related vocabularies that could be used in a dataset or linkset description. For more information about the state of provenance vocabularies, the interested reader is recommended [[PROV-XG]].
The Provenance Ontology (PROV-O) [[PROV-O]] is a W3C candiate recommendation for representing provenance information about documents, datasets, workflow runs, etc. It is broadly based on the Open Provenance Model [[OPM]]. It is capable of expressing complex provenance relationships.
The Provenance, Authoring and Versioning Ontology (PAV) [[PAV]] provides a comprehensive set of relationships for capturing basic provenance information.
The Provenance Vocabulary [[PRV]]] is another lightweight vocabulary of provenance predicates with an emphasis on data creation and data access on the Web.
Defined as an extension to VoID, the vocabulary for data and dataset provenance (voidp) [[VOIDP]] is a vocabulary for defining provenance relationships of data and datasets. The vocabulary focuses on four specific pieces of provenance information:
"for a piece of data, x :
- when was x derived,
- how was x derived,
- what data had been used to derive x,
- who carried out the transformations that resulted in the current value of x." [[VOIDP]]
These are a subset of the information that needs to be captured for the Open PHACTS linksets.
Complete list of suggested URIs.
This section lists suggested vocabulary terms for the dataset topics metadata that are relevant for Open PHACTS. The term in bold is the preferred URI.
Below are the terms from the frequency of change vocabulary.
The ChemSpider site already has a VoID descriptor available from http://rdf.chemspider.com/void.rdf. This has been created with a previous version of the VoID specification. Below is a suggested updated version which conforms with the requirements of this specification.
@prefix : <http://rdf.chemspider.com/void.ttl#>. @prefix dcterms: <http://purl.org/dc/terms/>. @prefix foaf: <http://xmlns.com/foaf/0.1/> . @prefix freq: <http://purl.org/cld/freq/> . @prefix pav: <http://purl.org/pav/>. @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>. @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>. @prefix skos: <http://www.w3.org/2004/02/skos/core#>. @prefix voag: <http://voag.linkedmodel.org/schema/voag#> . @prefix void: <http://rdfs.org/ns/void#>. @prefix xsd: <http://www.w3.org/2001/XMLSchema#>. # Metadata about this file <http://rdf.chemspider.com/void.ttl> a void:DatasetDescription; dcterms:title "A VoID Description of the ChemSpider Dataset"@en; dcterms:description """This is an example VoID description for the ChemSpider dataset. It is derived from the existing VoID description and updating it to the latest version of the VoID specification."""@en; pav:createdBy <http://www.cs.man.ac.uk/~graya/me.ttl>; pav:createdOn "2012-05-02T14:48:03Z"^^xsd:dateTime; pav:lastUpdateOn "2012-08-10T09:32:49Z"^^xsd:dateTime; pav:derivedFrom <http://rdf.chemspider.com/void.rdf>; foaf:primaryTopic :chemSpiderDataset; . # Description of the ChemSpider dataset :chemSpiderDataset # General metadata a void:Dataset; dcterms:title "ChemSpider"@en; dcterms:description "ChemSpider's Public Dataset"@en; foaf:homepage <http://rdf.chemspider.com/>; foaf:page <http://www.chemspider.com/>; dcterms:license <http://www.chemspider.com/Disclaimer.aspx>; void:uriSpace "http://rdf.chemspider.com/"^^xsd:string; #Provenance dcterms:publisher <http://www.chemspider.com/>; dcterms:created "2007-03-01T00:00:00"^^xsd:dateTime; dcterms:modified "2012-10-16T00:00:00"^^xsd:dateTime;#Subsets void:subset :chemSpiderDataset_chembl_subset,:chemSpiderDataset_drugbank_subset; #Vocabularies, topics, resources void:vocabulary <http://purl.org/dc/elements/1.1/>, <http://purl.org/dc/terms/>, <http://www.openarchives.org/ore/terms/>, <http://www.polymerinformatics.com/ChemAxiom/ChemDomain.owl#>, <http://xmlns.com/foaf/0.1/>; dcterms:subject <http://dbpedia.org/resource/Molecule>; void:exampleResource <http://rdf.chemspider.com/2157>; #Dataset Access void:sparqlEndpoint <http://rdf.chemspider.com/sparql>; #Update Frequency voag:frequencyOfChange freq:continuous; #Other Metadata # Technical features void:feature <http://www.w3.org/ns/formats/RDF_XML>; # Dataset statistics void:triples "1157624328"^^xsd:nonNegativeInteger; . :chemSpiderDataset_chembl_subset #General Metadata a void:Dataset; dcterms:title "ChemSpider ChEMBL Subset"@en; dcterms:description "The slice of ChemSpider data that corresponds to ChEMBL molecules."@en; #Provenance pav:retrievedFrom <ftp://ftp.ebi.ac.uk/pub/databases/chembl/ChEMBLdb/releases/chembl_13/chembl_13.sdf.gz>; pav:retrievedOn "2012-08-02T10:23:56Z"^^xsd:dateTime; pav:retrievedBy <http://www.chemspider.com/> ; #Dataset Access void:dataDump <https://www.dropbox.com/sh/6zboa8z9i9vrzyl/7NxayhkUH0/ChEMBL20120731.zip>; . # Description of the ChemSpider subset relating to DrugBank :chemSpiderDataset_drugbank_subset #General Metadata a void:Dataset; dcterms:title "ChemSpider DrugBank Subset"@en; dcterms:description "Data corresponding to DrugBank."@en; #Provenance pav:retrievedFrom <http://www.drugbank.ca/system/downloads/current/structures/all.sdf.zip>; pav:retrievedOn "2012-08-02T10:24:06Z"^^xsd:dateTime; pav:retrievedBy <http://www.chemspider.com/> ; #Dataset Access void:dataDump <https://www.dropbox.com/sh/6zboa8z9i9vrzyl/qcFZzbLM77/DrugBank20120731.zip>; .
Below we provide the VoID document for the ChEMBL-RDF dataset, which
is a conversion of the ChEMBL database. The VoID file would be
@prefix : <http://linkedchemistry.info/void.ttl#>. @prefix dcterms: <http://purl.org/dc/terms/>. @prefix foaf: <http://xmlns.com/foaf/0.1/> . @prefix freq: <http://purl.org/cld/freq/> . @prefix pav: <http://purl.org/pav/>. @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>. @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>. @prefix skos: <http://www.w3.org/2004/02/skos/core#>. @prefix voag: <http://voag.linkedmodel.org/schema/voag#> . @prefix void: <http://rdfs.org/ns/void#>. @prefix xsd: <http://www.w3.org/2001/XMLSchema#>. # Metadata about this file <> a void:DatasetDescription; dcterms:title "ChEMBL-RDF VoID Description"@en; dcterms:description """This is the VoID description for a ChEMBL-RDF dataset."""@en; pav:createdBy <http://egonw.github.com/#me> ; pav:createdOn "2012-08-12T16:56:07Z"^^xsd:dateTime; pav:lastUpdateOn "2012-09-14T12:21:12Z"^^xsd:dateTime; pav:previousVersion <http://semantics.bigcat.unimaas.nl/chembl/v13_ops/chembl-rdf-void.ttl>; foaf:primaryTopic :chemblrdf_dataset. :chemblrdf_dataset # General metadata a void:Dataset; dcterms:title "ChEMBL-RDF 13.OPS.2"@en; dcterms:description "The ChEMBL database in RDF format."@en; foaf:homepage <http://github.com/egonw/chembl.rdf/>; foaf:page <http://www.biosharing.org/biodbcore-000015>; dcterms:license <http://creativecommons.org/licenses/by-sa/3.0/> ; void:uriSpace "http://linkedchemistry.info/chembl/"^^xsd:string ; # Provenance pav:version "v13_ops"; pav:previousVersion <http://semantics.bigcat.unimaas.nl/chembl/v13_ops/chembl-rdf-void.ttl#chemblrdf_dataset>; pav:importedFrom :chembl_dataset; pav:importedBy <http://egonw.github.com/#me> ; pav:importedOn "2012-05-15T15:34:40Z"^^xsd:dateTime; pav:createdWith <https://github.com/openphacts/chembl.rdf>; # Subsets void:subset :chemblrdf_compounds, :chemblrdf_targets ; # Vocabularies, topics, resources void:vocabulary <http://www.w3.org/1999/02/22-rdf-syntax-ns#>, <http://www.w3.org/2000/01/rdf-schema#>, <http://www.w3.org/2002/07/owl#>, <http://www.w3.org/2001/XMLSchema#>, <http://purl.org/dc/elements/1.1/>, <http://purl.org/ontology/bibo/>, <http://xmlns.com/foaf/0.1/>, <http://purl.org/spar/cito/>, <http://www.w3.org/2004/02/skos/core#> , <http://purl.obolibrary.org/obo#>, <http://www.blueobelisk.org/ontologies/chemoinformatics-algorithms/#>, <http://www.blueobelisk.org/chemistryblogs/>, <http://www.nmrshiftdb.org/onto#>, <http://www.ifomis.org/bfo/1.1/snap#>, <http://semanticscience.org/resource/>, <http://purl.org/obo/owl/CHEBI#>; # Update frequency #Need to verify the update frequency! voag:frequencyOfChange freq:semiannual; # Other metadata void:distinctSubjects "18018451"^^xsd:integer ; . :chembl_dataset # Metadata about the original data source a dcterms:Dataset; dcterms:title "ChEMBL"@en; dcterms:description """ChEMBL is a database of bioactive drug-like small molecules, it contains 2-D structures, calculated properties (e.g. logP, Molecular Weight, Lipinski Parameters, etc.) and abstracted bioactivities (e.g. binding constants, pharmacology and ADMET data)."""@en; foaf:homepage <http://www.ebi.ac.uk/chembl/>; dcterms:license <http://creativecommons.org/licenses/by-sa/3.0/> ; pav:version "13"^^xsd:integer ; dcterms:publisher <http://www.ebi.ac.uk/chembl/>; dcterms:created "2012-02-29T00:00:00Z"^^xsd:dateTime; dcterms:modified "2012-02-29T00:00:00Z"^^xsd:dateTime; . :chemblrdf_compounds # Subset metadata a void:Dataset ; dcterms:title "ChEMBL Molecules"@en; dcterms:description "The subset of ChEMBL data relating to molecules."@en; void:uriSpace "linkedchemistry.info/chembl/molecule/"^^xsd:string ; dcterms:subject <http://dbpedia.org/resource/Molecule> ; void:exampleResource <http://linkedchemistry.info/chembl/molecule/m1>; void:dataDump <http://semantics.bigcat.unimaas.nl/chembl/v13_ops/compounds.nt.gz> ; . :chemblrdf_targets # Subset metadata a void:Dataset ; dcterms:title "ChEMBL Targets"@en; dcterms:description "The subset of ChEMBL data relating to targets which are single proteins."@en; void:uriSpace "linkedchemistry.info/chembl/target/"^^xsd:string ; dcterms:subject <http://dbpedia.org/resource/Protein> ; void:exampleResource <http://linkedchemistry.info/chembl/target/t1>; void:dataDump <http://semantics.bigcat.unimaas.nl/chembl/v13_ops/targets.nt.gz> ; .