RFC 7231, "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content", June 2014

Note: This RFC has been obsoleted by RFC 9110

Errata ID: 5448
Status: Rejected
Type: Technical
Publication Format(s) : TEXT
Reported By: Magnar Ovedal Myrtveit
Date Reported: 2018-08-02
Rejected by: Alexey Melnikov
Date Rejected: 2018-09-04

Section 7.1.1.1 says:

Recipients of a timestamp value in rfc850-date format, which uses a
two-digit year, MUST interpret a timestamp that appears to be more
than 50 years in the future as representing the most recent year in
the past that had the same last two digits.

It should say:

Recipients of a timestamp value in rfc850-date format, which uses a
two-digit year, MUST interpret a timestamp that appears to be more
than 200 years in the future as representing the most recent date in
the past that also matches the timestamp.

Notes:

The combination of day-of-the-week, day-of-the-month, month, and the two last digits of the year repeats every 400 years. For example, "Friday, 01-Jan-00 00:00:00 GMT" (as formatted by rfc850) happens in the years ...1300, 1700, 2100, 2500, 2900...

With the original text, "Friday, 01-Jan-00 00:00:00 GMT" is interpreted as year 2000, since year 2100 is more than 50 years in the future, and year 2000 is the most recent year in the past with the same last two digits as 2100. However, if it really was year 2000, it should have said "Saturday, 01-Jan-00 00:00:00 GMT". So it would make more sense to interpret it as either year 1700 or year 2100. The corrected text interprets it as year 2100.

"Monday, 01-Jan-00 00:00:00 GMT" happens in years ...1100, 1500, 1900, 2300, 2700..., and is interpreted as year 1900, since 2300 is more than 200 years in the future.
--VERIFIER NOTES--
This changes the original intent of the text, so errata mechanism is not suitable.

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