Subject: Genart telechat review of draft-murchison-tzdist-tzif-15

From: Dale Worley <[email-masked]>
Date: Wed, 24 Oct 2018 20:48:02 -0700

Reviewer: Dale Worley
Review result: Ready with Nits

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Document:  draft-murchison-tzdist-tzif-15
Reviewer:  Dale R. Worley
Review Date:  2018-10-24
IETF LC End Date:  2018-10-09
IESG Telechat date:  2018-10-25

Summary:
       This draft is basically ready for publication, but has nits
       that should be fixed before publication.

There are two remaining nits:

The semantics of the various data items -- what they mean and how they
are to be used in processing -- is only hinted at.  I suspect that the
draft is targeted at members of the community who already thoroughly
understand the semantics of the data items (based on their names), but
this is not stated.  There is a reference:

   see "Sources for Time
   Zone and Daylight Saving Time Data" [tz-link] for more-detailed
   information about civil timekeeping data and practice

but it does not positively assert that [tz-link] provides the
specification of the data items in TZif.

It's very likely that this is Not A Problem within the community that
would use this specification, but that needs to be positively
ascertained, as there is no definitive statement in the draft itself.

3.2.  TZif Data Block

   time zone designations:  A series of octets constituting an array of
      NUL-terminated (0x00) time zone designation strings.  [...]
      The character encoding of time zone designation
      strings is not specified; however, see Section 4 of this document.

I think this should be expanded to "The character encoding of time
zone designation strings is not specified, other than that encoded
characters MUST NOT contain a NUL (0x00) octet.  However, see Section
4 of this document."  This is because some important multi-octet
encodings generate NUL octets, and while the TZif format does not fix
the encoding, certain encodings (o rather certain encoded characters)
MUST be forbidden.