A question hazardstatement element @type

Hi,

    

    Please tell me about the specification of @type ("trouble") of the
    hazardstatement element of DITA 1.3.

    
      
The specification of the @type value of the hazardstatement
        element is 

        "Available values are note, tip, fastpath, restriction,
        important, remember, attention, caution, notice, danger,
        warning, other, and - dita - use - conref - target ." .

      
The hazardstatement element is a specialization of the note
        element. "Inheritance + topic/note hazard-d/hazardstatement"

      
We can specify "trouble" for the @type value of the note
        element.

    
    Are there any special reasons for not including "trouble" in the
    value of @type in the hazardstatement element?

    

    Best regards,

    Aruga