WebVTT: The Web Video Text Tracks Format (WebVTT1)- Change Summary

Technical Changes (normative)

* added a ::cue-region(id) pseudo-element to select regions by ID in CSS

* disallowed external resources in a data URL in the STYLE section

* drop line: and position: settings with invalid linealign/colalign values

* change parsing of 'line' setting to accept non-integers

* change to region blocks instead of region headers

* make align:start/end not affect position or position alignment

* rename start/end for position alignment to left/right

* clarify what align:left/right do for vertical text

* move to using CSS text-wrap:balance instead of custom line wrapping algorithm

* add ruby-position and text-combine-upright to the list of supported properties

* add a non-CSS UA conformance class

* allow external language information to apply

* support all of HTML's character references

* avoid waiting for a LF before checking the WEBVTT signature

* rename "middle" to "center" throughout for consistency with CSS

* make  be bidi-isolated and use default background color on it

* add support for STYLE blocks



Editorial Changes

Structural Document Changes:

* Added new section explicitly documenting styling (1.3)

* Formalized conformance classes (2.1)

* Added unicode handling information (2.2)

* Made WebVTT comment block part of the WebVTT File structure (3.1)

* Added parsing rules for chapter titles (5.6)

* Removed rendering of cues in isolation - everything is rendered with
video (6.1)

* Moved CSS extensions into their own chapter (7) and added an intro for authors

* Added new Security and Privacy Considerations section

* Added an index of defined Terms

* Added an overview of the IDL