[3] RFC 867 - Daytime Protocol, 2021-01-24T15:35:06.000Z, 2021-03-10T06:22:59.283Z https://tools.ietf.org/html/rfc867
[1] NIST Internet Time Service (ITS) | NIST, 2021-01-16T00:01:31.000Z, 2021-01-16T07:39:36.047Z https://www.nist.gov/pml/time-and-frequency-division/time-distribution/internet-time-service-its
[2] ACTS 形式とは少し違う。