Datetime leaf node

@prefix omop: <https://w3id.org/omop/ontology/> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

omop:datetime a owl:DatatypeProperty,
        owl:FunctionalProperty ;
    rdfs:label "Datetime"^^xsd:string ;
    rdfs:comment "For Death: If you have date and time of death, populate death_datetime, otherwise leave NULL"@en,
        "For Measurement: This is not required, though it is in v6. If a source does not specify datetime the convention is to set the time to midnight (00:00:0000)"@en,
        "For Note Nlp: The date and time of the note processing."@en,
        "For Note: If time is not given set the time to midnight."@en,
        "For Observation: If no time is given set to midnight (00:00:00)."@en,
        "For Procedure Occurrence: If the procedure has a start time in the native date, use this field to house that information. This will be renamed in a future version to **PROCEDURE_START_DATETIME**."@en ;
    rdfs:domain omop:Event ;
    rdfs:range xsd:dateTime ;
    omop:omop_cdm_name "death.death_datetime#180 AS datetime"^^xsd:string,
        "measurement.measurement_datetime#138 AS datetime"^^xsd:string,
        "metadata.metadata_datetime#333 AS datetime"^^xsd:string,
        "note.note_datetime#188 AS datetime"^^xsd:string,
        "note_nlp.nlp_datetime#211 AS datetime"^^xsd:string,
        "observation.observation_datetime#161 AS datetime"^^xsd:string,
        "procedure_occurrence.procedure_datetime#103 AS datetime"^^xsd:string,
        "specimen.specimen_datetime#220 AS datetime"^^xsd:string .