Any [Arguments] that MUST be present in the Invocation
Optional
audOptional if equal to subject
Optional
causeAn OPTIONAL CID of the Receipt that enqueued the Task
The Command to eventually invoke
Expiration UTC Unix Timestamp in seconds (valid until)
Optional
iatIssued at time
Issuer DID (sender)
Optional
metaMeta (asserted, signed data) — is not delegated authority
Optional
nbf"Not before" UTC Unix Timestamp in seconds (valid from)
The nonce of the UCAN
Delegations that prove the chain of authority
Principal that the chain is about (the [Subject])
See
https://github.com/ucan-wg/invocation#invocation-payload