There is not a single DNR form that is valid for all 50 states. A person must fill out an advanced directive form in each state that they live. Although in some states advanced directives may be reciprocal, there are many states that have their own standards for advanced directives.
There are many states that require the advanced directive to be notarized such as West Virginia, Tennessee, Missouri, and North Carolina. Therefore, even if an advanced directive is produced in these states, it is null and void if not notarized. A possibly helpful document is called "Five Wishes", and is acknowledged in several states. "Five Wishes" can be downloaded from AgingWithDignity.org.