Optional
readA boolean that indicates that the Relying Party would like to fetch the previously-written blob associated with the asserted credential. Only valid during authentication.
Optional
supportOnly valid during registration.
Optional
writeAn opaque byte string that the Relying Party wishes to store with the existing credential. Only valid during authentication.
LargeBlob extension inputs
See
https://w3c.github.io/webauthn/#dictdef-authenticationextensionslargeblobinputs