Check for optional last accessed date for referenced resources

[aj-stein-gsa]

Constraint Task

In some cases, a back-matter/resource will not have an explicit publication date (to be encoded as prop[@name="published'], per #778. For those cases, we want to give OSCAL tool developers the option to define a property to indicate the last accessed date and time.

Intended Outcome

Define a constraint for prop[@name="last-accessed" and @ns="https://fedramp.gov/ns/oscal"]/@value checks the value is a date-time-with-timezone value.

Syntax Type

This is a FedRAMP constraint in the FedRAMP-specific namespace.

Allowed Values

There are no relevant allowed values.

Metapath(s) to Content

<!-- context -->
//back-matter

<!-- target -->
resource

<!-- constraint, because it's easy enough -->
<matches target="prop[@ns='https://fedramp.gov/ns/oscal' @name='last-accessed']" datatype="dateTime-with-timezone"/>

Purpose of the OSCAL Content

No response

Dependencies

No response

Acceptance Criteria

• All OSCAL adoption content affected by the change in this issue have been updated in accordance with the Documentation Standards.
  • Explanation is present and accurate
  • sample content is present and accurate
  • Metapath is present, accurate, and does not throw a syntax exception using oscal-cli metaschema metapath eval -e "expression".
• All constraints associated with the review task have been created
• The appropriate example OSCAL file is updated with content that demonstrates the FedRAMP-compliant OSCAL presentation.
• The constraint conforms to the FedRAMP Constraint Style Guide.
  • All automated and manual review items that identify non-conformance are addressed; or technical leads (David Waltermire; AJ Stein) have approved the PR and “override” the style guide requirement.
• Known good test content is created for unit testing.
• Known bad test content is created for unit testing.
• Unit testing is configured to run both known good and known bad test content examples.
• Passing and failing unit tests, and corresponding test vectors in the form of known valid and invalid OSCAL test files, are created or updated for each constraint.
• A Pull Request (PR) is submitted that fully addresses the goals section of the User Story in the issue.
• This issue is referenced in the PR.

Other information

This task is part of #815 and will resolve #778 once implemented.