-Humane OWL (HOWL) is a syntax for RDF and OWL designed for manual editing. By allowing human-readable labels to be used in place of IRIs, and providing convenient syntax for OWL annotations and expressions, HOWL files can be used like source code with tools such as GitHub, then translated into any other RDF or OWL format for use with other tools.
An interactive demonstration of HOWL is available at <http://try.humaneowl.com>. Code and documentation are available at <https://github.com/ontodev/howl>, under an open source (BSD) license.
assay definition: A planned process with the objective to produce information about the material entity that is the evaluant, by physically examining it or its proxies. > comment: An OWL annotation on the definition. type:> owl:Class equivalent to:>> achieves_planned_objective some 'assay objective'
An RDF graph is composed of IRIs and literal values. IRIs and graphs can be hard for humans to read and write: IRIs because they are often long and opaque; graphs because they are less structured than familiar tables or hierarchies, and because some elements such as OWL annotations and logical expressions require compound structures made of many nodes. HOWL applies old and new techniques to these problems. 1) IRIs a) BASE: used to resolve relative IRIs (like Turtle) b) PREFIX: used to shorten IRIs (like Turtle) c) LABEL: used in place of IRIs (like JSON-LD) 2) Literals a) TYPE: sets the default datatype or language tag for a predicate (like JSON-LD) b) no quotation marks c) multi-line literals (using indentation) 3) Graphs a) GRAPH: sets the current named graph or default graph, allowing for RDF datasets (quads) b) “stanzas” group statements for a subject (like Turtle) c) OWL annotations are statements prefixed with “>” d) Manchester syntax logical expressions (like Protégé)
The 0.2.0 release of HOWL converts HOWL to N-Quads, N-Triples, and JSON. Other existing tools can then convert NQuads and N-Triples to any other RDF or OWL format. We aim to support lossless translation from HOWL to RDF and back. We also plan to include a default HOWL context with standard prefixes and labels for OBO projects. Work-inprogress toward a HOWL version of the Ontology for biomedical investigations is available at <https://github.com/ontodev/obi-howl>.
This project was supported by the Immune Epitope Database under NIH contract HHSN272201200010C. # Define labels for later use.
LABEL rdf:type: type LABEL rdfs:label: label LABEL rdfs:comment: comment LABEL owl:equivalentClass: equivalent to # Define default datatypes or language tags. TYPE label:> @en # Declare some supporting terms. obo:IAO_0000115 label: definition type:> owl:AnnotationProperty obo:OBI_0000441 label: assay objective type:> owl:Class # Declare 'assay' and provide its label. obo:OBI_0000070 label: assay obo:IAO_0000115 rdfs:label "definition"@en ; a owl:AnnotationProperty . obo:OBI_0000417 rdfs:label "achieves_planned_objective"@en ; a owl:ObjectProperty . obo:OBI_0000441 rdfs:label "assay objective"@en ; a owl:Class . obo:OBI_0000070 rdfs:label "assay"@en ; obo:IAO_0000115 "A planned process with the objective to produce information about the material entity that is the evaluant, by physically examining it or its proxies." ; _:b0 a owl:Axiom ; owl:annotatedSource obo:OBI_0000070 ; owl:annotatedProperty obo:IAO_0000115 ; owl:annotatedTarget "A planned process with the objective to produce information about the material entity that is the evaluant, by physically examining it or its proxies." ;
rdfs:comment "An OWL annotation on the equivalence axiom." .
a owl:Class ; owl:equivalentClass _:b1 . _:b1 a owl:Restriction ; owl:onProperty obo:OBI_0000417 ; owl:someValuesFrom obo:OBI_0000441 .
Fig.3. Turtle syntax equivalent to HOWL in Figs. 1 and 2