Binary on the FHIR specification website.

A resource that represents the data of a single raw artifact as digital content accessible in its native format. A Binary resource can contain any content, whether text, image, pdf, zip archive, etc.

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

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