dcterm:PeriodOfTime

[Sveino]

Summary

When converting between TriG / JSON-LD and CIMXML, we need special handling of the DCAT temporal extent construct based on
dcterms:PeriodOfTime.

DCAT 3 defines temporal coverage using a compound structure (blank node or resource) which is not supported by CIMXML.
(RDF/XML as a syntax supports this, but CIMXML does not.)

Relevant specification:
https://www.w3.org/TR/vocab-dcat-3/#Class:Period_of_Time

Background

In DCAT 3, temporal coverage is expressed using:

• dct:temporal → dcterms:PeriodOfTime

with properties:

• dcat:startDate

• dcat:endDate

This requires a compound RDF node, typically serialized as a blank node in TriG / JSON-LD.

CIMXML does not support compound objects / blank nodes, and therefore cannot represent dcterms:PeriodOfTime directly.

Supported Representation (TriG / JSON-LD)

TriG and JSON-LD SHALL support the full DCAT compound structure.

Example:

dct:temporal       [ rdf:type        dct:PeriodOfTime;
                                 dcat:startDate  "2014-12-31T23:00:00Z"^^xsd:dateTime ;
                                 dcat:endDate  "2015-01-01T23:00:00Z"^^xsd:dateTime ;
                               ];

Notes:

• dct:temporal range is dcterms:PeriodOfTime

• dcat:startDate and dcat:endDate are defined by DCAT 3

• The node is typically a blank node

CIMXML Handling (Flattened Representation)

For CIMXML output, the compound structure SHALL be flattened.
The dcterms:PeriodOfTime node is not serialized, and only its scalar properties are emitted.

Flattened CIMXML representation:

<dcat:startDate>2014-12-31T23:00:00Z</dcat:startDate>
<dcat:endDate>2015-01-01T23:00:00Z</dcat:endDate>

Important characteristics

• This is a lossy transformation

• The semantic grouping (dct:temporal → PeriodOfTime) is not preserved

• The meaning is retained implicitly by context (e.g. dataset temporal coverage)

Rules (Normative)

• TriG and JSON-LD SHALL support dct:temporal with dcterms:PeriodOfTime

• CIMXML SHALL NOT emit compound or blank-node structures

• CIMXML SHALL flatten dcterms:PeriodOfTime into:

• dcat:startDate

• dcat:endDate

• CIMXML SHALL NOT emit rdf:type dct:PeriodOfTime

• Datatypes SHALL be xsd:dateTime and expressed in UTC (Z)