ISSUE-45: Default ignorable code points

Default ignorable code points

Raised by:
Richard Ishida
Opened on:
The HTML specification should require user agents to implement the Unicode spec re Default Ignorable Code Points (Unicode Standard version 5.2, Chapter 5 (, section 5.21), including never displaying the directional formatting characters (LRM, RLM, LRE, RLE, LRO, RLO, and PDF) inappropriately (e.g. as empty boxes or advance widths) even if the underlying platform does not handle them properly. In particular, this must be the case for script dialog text, page titles, and tooltips.

Currently, directional formatting characters are most often displayed inappropriately in these context, since user agents mostly rely on the operating system to display the text in these contexts correctly, which does not happen because most LTR users' machines do not have RTL characters support installed. As a result, web applications are unable to use directional formatting characters around LTR text to make sure it is displayed correctly in an RTL context, since doing so will make it display incorrectly in the far more common LTR context.

Please add comments to bugzilla:

For implementation status see:

IMPORTANT: This issue was moved from our old review tracking system to the new tracker system. For previous mail relating to this issue, see:
Related Actions Items:
No related actions
Related emails:
  1. Review of tracker issues for best practices (part II) (from on 2015-03-28)
  2. I18N-ISSUE-45: Default ignorable code points [HTML5-bidi] (from on 2011-06-20)

Related notes:

No additional notes.

Display change log ATOM feed

Addison Phillips <>, Chair, Richard Ishida <>, Fuqiao Xue <>, Atsushi Shimono <>, Staff Contacts
Tracker: documentation, (configuration for this group), originally developed by Dean Jackson, is developed and maintained by the Systems Team <>.
$Id: index.php,v 1.326 2018/10/13 17:29:51 vivien Exp $