ISSUE-230: Forced display

Forced display

Forced display

Raised by:
Pierre-Anthony Lemieux
Opened on:
[The following is extracted from the liaison received from SMPTE at]

A forcedDisplay parameter shall be applicable to <p> elements and shall indicate that the element is to be displayed even if not explicitly activated. The forcedDisplay parameter shall be animatable.

Note: IMF Data Essence may be selected for presentation based on user preferences, as a result of user action, or by default. Such Data Essence is however displayed only if either (a) explicitly activated as a result of user action or (b) identified as “forced”.
Related Actions Items:
No related actions
Related emails:
  1. Re: {agenda} TTWG Meeting 2014-12-11 (from on 2014-12-11)
  2. {agenda} TTWG Meeting 2014-12-11 (from on 2014-12-10)
  3. {minutes} TTWG Meeting 27/11/2014 (from on 2014-11-27)
  4. {agenda} TTWG Meeting 27/11/2014 (from on 2014-11-26)
  5. {agenda} TTWG Meeting 29/5/2014 (from on 2014-05-28)
  6. Re: ISSUE-312 (forcedDisplay should be in ttm): forcedDisplay attribute is metadata so should be in ttm not tts namespace [TTML IMSC 1.0] (from on 2014-05-27)
  7. {minutes} TTML Meeting of 24/10/13 (from on 2013-10-24)
  8. RE: TTML Agenda for 24/10/13 (from on 2013-10-23)
  9. TTML Agenda for 24/10/13 (from on 2013-10-23)
  10. ISSUE-230 (Forced display): Forced display [] (from on 2013-05-30)

Related notes:

I don't understand this use case. Why would an author explicitly mark content that a user can force to be displayed even though it is not active?

Glenn Adams, 30 May 2013, 20:14:05

[glenn]: perhaps add a 'force' role?

6 Jun 2013, 14:44:13

[pal]: use case: forces the display of those subtitles that are associated with klingon speech and that all users should see -- the other subtitles, e.g. english subtitle over english speech, should be shown only to those users that have elected to do so.

6 Jun 2013, 14:58:20

Pal: P2

Philippe Le Hégaret, 24 Oct 2013, 15:43:11

Move up to P1.

Planned use by IMSC. In use by CFF-TT. Widespread use in Blu Ray.

Suggest defining inheritable tts:forcedDisplay with the following properties
Values: false | true
Initial: false
Applies to: body, div, p, region, span
Inherited: yes
Percentages: N/A
Animatable: discrete

Pierre-Anthony Lemieux, 10 Nov 2013, 07:37:22

With the addition of a 'condition' attribute and a 'forced' bound parameter for use with a parameter-function, it is possible to express conditional content/styling predicated upon the external setting of a 'forced' parameter.

See .

Glenn Adams, 26 Nov 2014, 02:17:50

Display change log ATOM feed

David Singer <>, Nigel Megitt <>, Chairs, Thierry Michel <>, Philippe Le Hégaret <>, Staff Contacts
Tracker: documentation, (configuration for this group), originally developed by Dean Jackson, is developed and maintained by the Systems Team <>.
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