- From: David Singer <singer@apple.com>
- Date: Sat, 30 Sep 2017 17:47:23 -0700
- To: Timed Text Working Group <public-tt@w3.org>
TTML is based in XML, but experience over the years has shown that the ‘X’ (extensible) is deeply problematic. When a specification is revised, either all the new features are in a new namespace, which makes documents messy and hard to read, or they have to fit into places where ‘any’ element or ‘any’ attribute is allowed in the prior grammar. Unfortunately, the latter leaves the new elements/attributes very much in a second-class-citizen state. If instead, a new namespace and grammar is minted, then the documents are no longer recognizable to and processable by a reader written to recognize the old namespace ID, even if the extensions and new elements can be ignored and fallback behavior is acceptable. When the incorporation of elements designed by other bodies is included, the result can be a bewildering mess. This has sometimes led to attempts to ‘make native’ these elements, and effectively copy their specification from the external definition into the revision; but this raises questions of attribution and backwards compatibility. I recommend the group consider a re-design using a more flexible and less problematic base syntax. David Singer Manager, Software Standards, Apple Inc.
Received on Sunday, 1 October 2017 00:47:46 UTC