Re: ISSUE-358 (Sequence support): Add identifier support for related ordered sequences of documents [TTML2]

From: Glenn Adams <glenn@skynav.com<mailto:glenn@skynav.com>> Date: Wednesday, 10 December 2014 18:33

Now that I've introduced a generic metadata item element, it is better to satisfy this requirement by simply defining new named metadata items, representing it as:

<ttm:item name="sequenceIdentifier">string</ttm:item>

<ttm:item name="sequenceNumber">positiveInteger</ttm:item>

ttm:item isn't permitted on tt:tt though, which means that there's a deep parsing requirement to discover this data, so it doesn't satisfy the requirement.

Incidentally, if you were to add this concept to isd:isd then the isd:sequence element would be unnecessary except as a root element in an XML document, since you could represent a sequence of ISDs using the same syntax. I see that isd:sequence and isd:isd do permit content from Metadata.class whereas tt:tt does not – I'm not sure why there's a difference there, in principle anyway.



On Wed, Dec 10, 2014 at 9:56 AM, Timed Text Working Group Issue Tracker <sysbot+tracker@w3.org<mailto:sysbot+tracker@w3.org>> wrote:
ISSUE-358 (Sequence support): Add identifier support for related ordered sequences of documents [TTML2]

http://www.w3.org/AudioVideo/TT/tracker/issues/358


Raised by: Nigel Megitt
On product: TTML2

In an authoring environment that creates an ordered sequence of TTML documents that collectively form some kind of coherent representation collectively, such as a sequence of documents created 'live', it is useful to be able to identify at the root level, i.e. with minimal parsing requirements, that:

1. A collection of documents belongs to the same sequence and
2. The relative ordering of a document within the sequence.

This also relates to Change Proposal 25 and Issue-288, and the proposal made in the November TPAC meeting.

Modified proposal now includes a sequence number:

Metadata attribute ttm:sequenceIdentifier
Considered significant on tt:tt only.
Optional attribute.
Type xs:string
Description: The ttm:sequenceIdentifier metadata attribute can be used to distinguish between sequences of documents where the documents within a sequence are related to each other but there is not necessarily any relationship between different sequences.

Metadata attribute ttm:sequenceNumber
Considered significant on tt:tt only.
Optional attribute.
Type xs:positiveInteger
Description: The ttm:sequenceNumber metadata attribute can be used to sort documents with the same sequenceIdentifier into a defined order. Two documents with the same sequenceIdentifier SHOULD NOT have the same sequenceNumber, if sequenceNumber is used.



Note that this proposal mirrors work happening in EBU but is my proposal and not an EBU proposal, for the avoidance of doubt.