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There is some disagreement about the default value for line alignment: 3.1 Text Track Cues - line alignment default is start 4.4.2 WebVTT cue settings - line alignment default is middle 5.1 WebVTT file parsing - line alignment default is start
This is about the vertical alignment for horizontal text, which is a new feature. It specifies how the lines in a cue box are default positioned between the top and the bottom of the cue box. We hadn't specified this before, but we haven't really had the concept of an explicit cue box either. I currently think we should use "start" as the default alignment so that if the cue box gets filled with more text (e.g. via paint-on text), the space is used better. Let me know if you think otherwise. "line alignment" in 3.1 relates to the second part of the "line:" setting and defaults to "start", so this is correct. In 4.4.2, the note is wrong and should say "start". 5.1 "start" as default for line alignment is correct.
Setting to v1 since this is about the position/alignment confusion.
Fixed in https://github.com/w3c/webvtt/commit/f590d2c8e30655f6ad2bea2dd8a50af513ae8b2b