Sales Forms: Document Type

Hi all,

I am trying to set a search define up that works on all sales forms, rather than create an alternate one for each form. I know I can get access to generic sections of the form using the following:

$[$4.0.0]

Which I know can get me the BP code for example, but I wish to extract the document type from the form, does anyone know if this is possible? or what number I would be after?

I know that $[$1.0.0] is the add/update button for example, the few numbers I have tried haven't yielded the correct results....

Is the a guide or list that contains these references??

All help is much appreciated.

Kind Regards

Matthew