Locking an AutoCAD file

I'm running AutoCAD 2008 and I want to send a cad file to someone, but I don't want them to change the drawing itself. I don't want to save the file as a bmp or pdf, because the quality of the drawing becomes unclear. So basically I want to lock the drawing, not the layers. Does anyone know if whether or not this can be done?

I answered your question where you first posted it.

I tried the program (DWGguardTNT), both in model and paper space, but I kept getting an error message (in spanish) and it automatically aborts the VLX file. Am I loading it incorrectly or does the program not work with AutoCAD 2008?

I don't want to save the file as a bmp or pdf, because the quality of the drawing becomes unclear.

Why are your pdf's unclear?

What pdf writer are you using?

Please don't start multiple threads asking the same question.

Visually when you plot a PDF next to a DWG file, you virtually cannot tell any difference at all with the naked eye. If you still want to believe that a PDF is not "good enough" then just send a DWF of the file. If someone can open a DWG then they can open a DWF.

I tried an experiment using 2010 and created a DWF file. I saved it to my desktop. I then renamed it as a DWG file. I tried to open it with AutoCAD but it failed.

Styk: When you "If say someone can open a DWG then they can open a DWF" what exactly were you referring to? Open it with what? A viewer? Yes. With AutoCAD? By my experience the answer would be "No."

Open it with what? A viewer? Yes. With AutoCAD? By my experience the answer would be "No."

This is correct.

Thanks. For a moment there I thought I had messed up the creation of the DWF file and that's why it failed to open even though I renamed it as a DWG file.