Well, IMHO, if ISO-9000, 9001, or 9004 does not specifically give the official ISO definition of a certain term they use (such as “should”) the most reasonable thing to do is use the normal, everyday (dictionary?) definition based on the context of the sentence. To me “should” does not mean you have to do something, or 'this you will do, and you decide how to do it' or something “must be done or a suitable alternative approach”. Where do those definitions come from? There must be a reason they use “should” instead of “shall”. To me, should means “ought to, but don’t have to”, i.e. “You should get your Mother a gift on Mother’s Day” or “you should check your tire pressure every week”. Or, as Howard said, recommendation is a good synonym.
As I said, JMHO.
