ISSUE-275: Improve compatibility with line height 'normal' and CSS/XSL-FO implementations.

line-height-normal-120

Improve compatibility with line height 'normal' and CSS/XSL-FO implementations.

State:

CLOSED

Product:

TTML 1.0

Raised by:

Glenn Adams

Opened on:

2013-08-23

Description:

Implementations of CSS and XSL-FO generally interpret line height 'normal' as 120% of the font size, rather than 100%. Both CSS and XSL-FO define this as implementation dependent, but recommend a value from 100% to 120% of relevant font size. At present, TTML proposed using 100%, but this turns out to be inadequate from a 'readability' perspective, and essentially forces authors to always specify some value that is more reasonable. For these reasons, TTML should use 120% instead of 100% to improve interoperability with existing presentation processors (based on CSS and XSL-FO) and also author expectations and readability (a11y).

Related Actions Items:

No related actions

Related emails:

1. Re: Line Height stacking strategy algorithm - approval needed (from pal@sandflow.com on 2014-01-22)
2. Re: Line Height stacking strategy algorithm - approval needed (from pal@sandflow.com on 2014-01-21)
3. Re: Line Height stacking strategy algorithm - approval needed (from glenn@skynav.com on 2014-01-20)
4. Re: Line Height stacking strategy algorithm - approval needed (from nigel.megitt@bbc.co.uk on 2014-01-20)
5. Re: Line Height stacking strategy algorithm - approval needed (from pal@sandflow.com on 2014-01-17)
6. Line Height stacking strategy algorithm - approval needed (from nigel.megitt@bbc.co.uk on 2014-01-17)
7. Minutes for 12/12/13 (from nigel.megitt@bbc.co.uk on 2013-12-12)
8. TTWG Agenda for 12/12/13 (from nigel.megitt@bbc.co.uk on 2013-12-11)
9. Re: TTWG Agenda for 5/12/13 (from nigel.megitt@bbc.co.uk on 2013-12-11)
10. Re: TTWG Agenda for 5/12/13 (from glenn@skynav.com on 2013-12-11)
11. RE: TTWG Agenda for 5/12/13 (from mdolan@newtbt.com on 2013-12-10)
12. TTWG Agenda for 5/12/13 (from nigel.megitt@bbc.co.uk on 2013-12-04)
13. Re: TTML Agenda for 21/11/13 (from cyril.concolato@telecom-paristech.fr on 2013-11-21)
14. Re: TTML Agenda for 21/11/13 (from glenn@skynav.com on 2013-11-21)
15. Re: TTML Agenda for 21/11/13 (from tmichel@w3.org on 2013-11-21)
16. TTML Agenda for 21/11/13 (from nigel.megitt@bbc.co.uk on 2013-11-20)
17. RE: TTML Agenda for 31/10/13 (from Sean.Hayes@microsoft.com on 2013-10-31)
18. TTML Agenda for 31/10/13 (from nigel.megitt@bbc.co.uk on 2013-10-30)
19. {minutes} TTML Meeting of 24/10/13 (from glenn@skynav.com on 2013-10-24)
20. RE: TTML Agenda for 24/10/13 (from mdolan@newtbt.com on 2013-10-23)
21. TTML Agenda for 24/10/13 (from nigel.megitt@bbc.co.uk on 2013-10-23)
22. {minutes} TTML Meeting of 17/10/13 (from glenn@skynav.com on 2013-10-17)
23. TTML Agenda for 17/10/13 (from Sean.Hayes@microsoft.com on 2013-10-17)
24. Re: ISSUE-284: value of lineHeight [TTML2] (from glenn@skynav.com on 2013-10-11)
25. RE: ISSUE-284: value of lineHeight [TTML2] (from mdolan@newtbt.com on 2013-10-11)
26. Re: ISSUE-284: value of lineHeight [TTML2] (from glenn@skynav.com on 2013-10-11)
27. ISSUE-284: value of lineHeight [TTML2] (from sysbot+tracker@w3.org on 2013-10-11)
28. TTML Agenda for 19/09/13 (from Sean.Hayes@microsoft.com on 2013-09-19)
29. No Meeting today 12-09-13 (from Sean.Hayes@microsoft.com on 2013-09-12)
30. Minutes for 05/09/13 (from nigel.megitt@bbc.co.uk on 2013-09-05)
31. Agenda for 05/09/13 (from glenn@skynav.com on 2013-09-04)
32. RE: TTML Agenda for 29/08/13 (from mdolan@newtbt.com on 2013-08-28)
33. TTML Agenda for 29/08/13 (from glenn@skynav.com on 2013-08-28)
34. ISSUE-275 (line-height-normal-120): Improve compatibility with line height 'normal' and CSS/XSL-FO implementations. [TTML 1.0] (from sysbot+tracker@w3.org on 2013-08-23)

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