Mike

I don't think it's strictly necessary to specify that we will try the longest granularity first, because we can tell from the length of the input data, together with the presence/absence of a '.' (fractional second separator), which of the granularities we should attempt to parse the input data against. Remember that by the time the parser tries to process the date/time, it will already have extracted the text using lengthKind and done any trimming.

Granularity Length
YYYY 4
YYYY-MM 7
YYYY-MM-DD 10
YYYY-MM-DDThh:mmTZD 17 or 22
YYYY-MM-DDThh:mm:ssTZD 20 or 25
YYYY-MM-DDThh:mm:ss.sTZD 22 or more but input data will contain '.'

(TZD can be Z or +hh:mm or -hh:mm)

Similarly for xs:time we would have,

Granularity Length
hh:mmTZD 6 or 11
hh:mm:ssTZD 9 or 14
hh:mm:ss.sTZD 11 or more but input data will contain '.'

Any other length of input data, or invalid data for the granularity matched, would be a processing error.

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
----- Forwarded by Steve Hanson/UK/IBM on 18/01/2012 16:29 -----

From: Mike Beckerle <mbeckerle.dfdl@gmail.com>
To: Steve Hanson/UK/IBM@IBMGB
Cc: dfdl-wg@ogf.org
Date: 17/01/2012 19:07
Subject: Issue 162: Re: [DFDL-WG] Proposed spec errata for calendarPattern I and T symbols

I reviewed this. The proposal looks fine as-is. I don't think the lack of gYear and gYearMonth types should affect the functionality offered. We left those out not because people don't want formats like that, but because we can handle those formats even without the additional types.

Do we need to clarify that the longest granularity is tried first, and this is greedy parsing? If the data matches one of the granularities there will be no backtracking to try others.

Proposal

Here is what is proposed to correct this. Note the T symbol is dropped. It was introduced to allow xs:dateTime to expect just a time, but that is not necessary (it was copied from IBM MRM). I've stated any alternatives that we can consider at the end.

Symbol Meaning Presentation Example
I ISO8601 Date/Time (Text) 2006-10-07T12:06:56.568+01:00
IU ISO8601 Date/Time (Text) 2006-10-07T12:06:56.568Z
with output "Z" if the
time zone is +00:00)

The 'I' symbol must not be used with any other symbol other than the 'escape for text' symbol. It represents calendar formats that match those defined in the restricted profile of the ISO8601 standard proposed by the W3C at http://www.w3.org/TR/NOTE-datetime.The formats are referred to as 'granularities'.

xs:dateTime. When parsing, the data must match one of the granularities. When unparsing, the fullest granularity is used.
xs:date. When parsing, the data must match one of the date-only granularities. When unparsing, the fullest date-only granularity is used. 'IU' is permitted for xs:date but the 'U' is effectively ignored as there is no time zone in the date-only granularities.
xs:time. When parsing, the data must match only the time components of one of the granularities that contains time components. When unparsing, the time components of the fullest granularity are used. The literal 'T' character is not expected in the data when parsing and is not output when unparsing.
The number of fractional second digits supported is implementation dependent but must be at least one.
For a granularity that omits components, when parsing the values for the omitted components are supplied from the Unix epoch 1970-01-01T00:00:00.000 .

Alternatives:

As above but don't support the first two granularities ('Year', 'Year and month') on the grounds that they are really matching xs:gYear and xs:gYearMonth.

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

Unless stated otherwise above:
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Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU

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Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number 741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU