Trace readers in a document

Hi all,

Wanna know if there are, or the best wat, to see if another person have seen or changed a document?

I know that you can see some things in "Drawing properties" and here make notes by yourselves.

Problem is that the AutoCad drawings (2008) that we make some times are given to other companies which are given advantage for them, steeling info from us in big projects. Ang guess it isn´t enough to make them read only.

Can you password these types of files?

Maybe this may help:

http://www.cadtutor.net/forum/showthread.php?t=9213