Encoding and decoding operations for a type usable as a persisted timestamp or diff.
Name of the codec.
This name is stored for the timestamp and diff when a stream is first created and the same timestamp and diff codec must be used for that stream afterward.
Encode a timestamp or diff for permanent storage.
This must perfectly round-trip Self through Codec64::decode. If the encode function for this codec ever changes, decode must be able to handle bytes output by all previous versions of encode.