lineHeight restriction should not preclude using the initial element

[cconcolato]

The current text says:

As implementation of the "normal" value is not uniform at the time of this writing, tts:lineHeight SHOULD NOT be set to "normal" and SHOULD be explicitly specified such that the specified style set of each p element contains a tts:lineHeight property whose value is not assigned by initial value fallback.

The intent is fine but the point about not being "assigned by initial value fallback" should be slightly modified to account for getting an initial value from the initial element whose value is different from "normal", something along the line of:

As implementation of the "normal" value is not uniform at the time of this writing, tts:lineHeight SHOULD NOT be set to "normal" and SHOULD be explicitly specified such that the specified style set of each p element contains a tts:lineHeight property whose value is not set to "normal". For that purpose, an initial element may be used to change the initial value "normal" to another value.

[css-meeting-bot]

The Working Group just discussed lineHeight restriction should not preclude using the initial element imsc#420.

The full IRC log of that discussion

<nigel> Topic: lineHeight restriction should not preclude using the initial element imsc#420
<nigel> github: https://github.com//issues/420
<nigel> Pierre: I plan to address this today, using the same text as in TTML2.
<nigel> Cyril: Fine