Minutes from DFDL WG call from last year:

  13.11. The DFDL property combination of dfdl:calendarTimezone and dfdl:calendarObserveDST
  is insufficient as it does not cater for different start dates for DST.  To achieve this we would have to
  relax dfdl:calendarTimeZone rules and allow it to take other formats, such as:
  a) Olson format (eg, "Europe/Paris")
  b) Unicode short time zone IDs as per (Unicode Locale Data Markup Language ) spec (eg, "frpar")
  The list of TZs for b) is here: http://lawiki.org/extensions/core/common/bcp47/timezone.xml
   Note there a special value for 'unknown' - "unk"  or "Etc/Unknown" - prefer to empty string?
   Agreed in principle,  raised action 153 to decide on the extended format to use.
   Noted that calendarObserveDST would still be honoured.for UTC values.

Action 153 proposal

Allow dfdl:calendarTimezone to be either UTC offset format or Olson format, as per option (a) above. Olson is the most  widely-used naming convention for time zones. Option (b) above refers to 5 character UN LOCODE codes (where possible) which identify locations and map to Olson time zones. However they are not well known and therefore less usable.

For representing 'not specified' time zone stick with the current errata (2.50) and use empty string. It seems more obvious than "Etc/Unknown" which is not defined in the Olson database, so would have to be handled as a special case.

When unparsing and dfdl:calendarPattern contains a formatting symbol for time zone (zzz, Z, VVVV etc) and the infoset value does not contain a time zone, it is a processing error. This matches the behaviour on parsing when the data does not contain a time zone but the pattern does. Spec should be clear on this.

When dfdl:calendarObserveDST is set to 'yes', it only makes sense if dfdl:calendarTimeZone is an Olson time zone. If it is a UTC offset then it should be a schema definition error if dfdl:calendarObserveDST is 'yes'.

Regards

Steve Hanson
Architect, Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh@uk.ibm.com
tel:+44-1962-815848





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