Path: utzoo!mnetor!uunet!husc6!hao!gatech!mcnc!decvax!decwrl!pyramid!oliveb!sun!gorodish!guy
From: guy@gorodish.Sun.COM (Guy Harris)
Newsgroups: comp.bugs.4bsd
Subject: Re: ctime(3) and leap seconds :-)
Message-ID: <38768@sun.uucp>
Date: 13 Jan 88 21:36:16 GMT
Sender: news@sun.uucp
Lines: 52
Keywords: ctime, leap second, epoch

I decided to see what RFC 822 had to say, if anything, on the subject of
representing dates.  It says:

     5.  DATE AND TIME SPECIFICATION

     5.1.  SYNTAX

     date-time   =  [ day "," ] date time        ; dd mm yy
                                                 ;  hh:mm:ss zzz

     day         =  "Mon"  / "Tue" /  "Wed"  / "Thu"
                 /  "Fri"  / "Sat" /  "Sun"

     date        =  1*2DIGIT month 2DIGIT        ; day month year
                                                 ;  e.g. 20 Jun 82

     month       =  "Jan"  /  "Feb" /  "Mar"  /  "Apr"
                 /  "May"  /  "Jun" /  "Jul"  /  "Aug"
                 /  "Sep"  /  "Oct" /  "Nov"  /  "Dec"

     time        =  hour zone                    ; ANSI and Military

     hour        =  2DIGIT ":" 2DIGIT [":" 2DIGIT]
                                                 ; 00:00:00 - 23:59:59

The reference to 23:59:59 is in a comment, so it's not clear whether this means
that 23:59:60 in an header would violate this specification or not.  Section
2.8 "; COMMENTS" says

          A semi-colon, set off some distance to  the  right  of  rule
     text,  starts  a comment that continues to the end of line.  This
     is a simple way of including useful notes in  parallel  with  the
     specifications.

which I infer means that it is a note, not a part of the specification.  From
that, I presume that it was assumed that everybody would know what the Right
Thing to do was and that they'd do it, and no formal specification was
necessary.  I don't know if they took the possibility of leap seconds into
account or not.

RFC 822 also refers to the document

     ANSI.  "Representations of Universal Time, Local  Time  Differen-
        tials,  and United States Time Zone References for Information
        Interchange," X3.51-1975.  American National Standards  Insti-
        tute:  New York (1975).

I don't know if this document says anything about leap seconds or not, because
I don't have a copy of it.
	Guy Harris
	{ihnp4, decvax, seismo, decwrl, ...}!sun!guy
	guy@sun.com