Recommended usage of the @dir attribute
    
  
    Typically, processors that fully support the Unicode
    Bidirectional Algorithm handle bidirectional text without the need to
    specify directionality in the DITA source, if the
      @xml:lang attribute is specified on the highest-level
    element.
The need to specify the @dir attribute primarily
      occurs in the following situations:
- Processors that do not fully support the Unicode Bidirectional Algorithm
- Documents that contain bidirectional text and characters with neutral bidirectionality
For the above situations, we recommend that DITA source documents,
      in addition to specifying the @xml:lang attribute,
      also specify the @dir attribute on the highest-level
      element that is necessary.