how to prompt for dtd?

Hi All,

I use Arbortext editor 6.0 M060, I can't set the promptnodtd to on because  i can't find it in the options list.

It should be set to on by default, but  when I open a document without a doctype declaration, the editor open it  in free-form XML mode, without prompting for the dtd.

Anyone can help me?

thanks

Sonia