Subject: DEFVAL for DateAndTimes

From: Randy Presuhn <[email-masked]>
Date: Tue, 4 Apr 2000 14:28:01 -0700 (PDT)

Hi -

A conversation with Dave Perkins in an Australian airport uncovered
a possible problem with RFCs 2592, 2591, and 2564.

RFC 2579's description of DateAndTime says:

|           field  octets  contents                  range
|           -----  ------  --------                  -----
|             1      1-2   year*                     0..65536
|             2       3    month                     1..12
|             3       4    day                       1..31
|             4       5    hour                      0..23
|             5       6    minutes                   0..59
|             6       7    seconds                   0..60
|                          (use 60 for leap-second)
|             7       8    deci-seconds              0..9
|             8       9    direction from UTC        '+' / '-'
|             9      10    hours from UTC*           0..13
|            10      11    minutes from UTC          0..59

These other documents have DEFVALs for DateAndTime of
'0000000000000000'H.  These values would be technically
illegal, and should probably be replaced with
'0000010100000000'H  when these documents are revised.

(Alternatively, we could just recognize the existing,
though technically illegal, practice and get on with
more interesting problems.  :-)

A related annoying question:  if the time has an offset of
00:00 from UTC, would the preferred value for byte 9 be a
'+' or a '-'?

 ------------------------------------------------------------------------
 Randy Presuhn           [email-masked]       http://www.bmc.com/
 Voice: +1 408 546-1006  BMC Software, Inc.  1-3141  2141 N. First Street
 Fax:   +1 408 965-0359  San Jose, California 95131  USA
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 Any relationship between my opinions and BMC's should be coincidental.
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---

From: Juergen Schoenwaelder <[email-masked]>
Date: Wed, 5 Apr 2000 12:41:00 +0200

[Please send any followups only to <[email-masked]> since this is
 really a cross WG issue.]

>>>>> Randy Presuhn writes:

Randy> A conversation with Dave Perkins in an Australian airport
Randy> uncovered a possible problem with RFCs 2592, 2591, and 2564.

Randy> RFC 2579's description of DateAndTime says:

[...]

Randy> These other documents have DEFVALs for DateAndTime of
Randy> '0000000000000000'H.  These values would be technically
Randy> illegal, and should probably be replaced with
Randy> '0000010100000000'H when these documents are revised.

The TN3270E-MIB (RFC 2561), TN3270E-RT-MIB (RFC 2562) and WWW-MIB (RFC
2594) also use this not strictly legal default value. I could not find
a single MIB which uses '0000010100000000'H.

Randy> (Alternatively, we could just recognize the existing, though
Randy> technically illegal, practice and get on with more interesting
Randy> problems.  :-)

I think that recognizing the existing, though technically illegal,
practice is the right thing to do. I will take care that the SMIng
definition of DateAndTime fixes this problem by explicitely allowing
the value '0000000000000000'H to indicate an unknown date and time
value. ;-)

Randy> A related annoying question: if the time has an offset of 00:00
Randy> from UTC, would the preferred value for byte 9 be a '+' or a
Randy> '-'?

I think both are valid and semantically identical. Not sure we need to
agree on a preferred value for byte 9 (although I would choose '+').

/js

-- 
Juergen Schoenwaelder      Technical University Braunschweig
<[email-masked]>  Dept. Operating Systems & Computer Networks
Phone: +49 531 391 3289    Bueltenweg 74/75, 38106 Braunschweig, Germany
Fax:   +49 531 391 5936    <URL:http://www.ibr.cs.tu-bs.de/~schoenw/>