braheem24...............we all can Google and find a better, cleaner and worthwhile, or valuable explanation, than set it up and type it ourselves like these thousands of one liner posts we mostly...
A man who has committed a mistake and doesn't correct it is committing another mistake.
I hope you have all.
Thanks but have not service manuals.
I believe he's stating the fact that, if you sell a pair of glasses to someone.
What you sold, the measurements you've taken, and their actual Rx must be given to the patient/customer upon request.