Background

UCO has the ability to represent certain timestamps based on sources like file systems or other metadata fields (e.g. from email). (See #420.) PDFs contain their own specialized timestamp fields, but UCO has no way of representing them yet.

The PDF specification provides for these time stamps:

CreationDate
ModDate

Requirements

Requirement 1

UCO must be able to represent the internally embedded creation time of a PDF file.

Requirement 2

UCO must be able to represent the internally embedded modification time of a PDF file.

Requirement 3

UCO must be able to represent the internally embedded access time of a PDF file.

Risk / Benefit analysis

Benefits

UCO would improve its timeline capabilities by representing these times.

Risks

There is a name pattern discrepancy between UCO's current observable:modifiedTime and observable:createdTime, versus the names in the specification. One name pattern must be selected, or the PDF specification should be deferred to.

Otherwise, this is an additive proposal.

Competencies demonstrated

Competency 1

Suppose a PDF is found to have both a creation and modification timestamp embedded.

Competency Question 1.1

Do the creation and modification time follow a sensible temporal ordering - modification occurs at or after creation time?

Ask for all PDF files in our knowledge base that have a creation time that comes definitively after the modification time.

SELECT ?nPdfFile
WHERE {
  ?nPdfFile
    a uco-observable:PDFFile ;
    uco-core:hasFacet ?nPdfFileFacet ;
    .

  ?nPdfFileFacet
    a uco-observable:PDFFileFacet ;
    drafting:pdfCreatedDate ?lCrDate ;
    drafting:pdfModDate ?lModDate ;
    .

  FILTER ( ?lCrDate > ?lModDate )
}

Result 1.1

Solution suggestion

To the observable:PDFFileFacet

Add property observable:pdfCreatedDate, cardinality 0..1, type xsd:dateTime.
Add property observable:pdfModDate, cardinality 0..1, type xsd:dateTime.

Coordination

Tracking in Jira ticket OC-256
[x] Administrative review completed
[x] Solutions Approval to be discussed in OC meeting, 2022-08-09
[x] Solutions Approval vote occurred, passing, on 2022-08-09
[x] Solutions development phase completed.
[x] Implementation merged into develop
[x] Milestone linked
[x] Documentation logged in pending release page

ucoProject / UCO

Add time properties to PDF File Facet #421