Different states?

I am sorry to be a bit thick but I am  afraid that I still do not understand the problem with pages that have different states.

If a page with a form works in a way that returns the form with error messages if it is incomplete - that is a different state (ie it has the same url but a different content). This, to me, is not a problem, if the random sample turns up a form I would test it normally, including testing the error response/s (i.e. the different states) to see that error messages were in text form etc.

The same goes for any other process whether using scripts or server responses.

As far as I can see there is no need to include “different states” in the sampling technique as it is inherent that any page that produces “different states” would be tested for all it’s states.

Regards
Richard