OperationDefinition on the FHIR specification website.

A formal computable definition of an operation (on the RESTful interface) or a named query (using the search interaction).

The body should be a list of valid JSON patches for OperationDefinition. For example, to update a Slot status to busy, this would be the body:

[
  {
    op: 'replace',
    path: '/status',
    value: 'busy',
  },
],