I know it's not your wording, but I hate "Systems SHALL be capable of processing resource instances containing the MUST SUPPORT data elements without generating an error or causing the application to fail. In other words, Systems SHOULD be capable of displaying the data elements for human use or storing it for other purposes." The second sentence is not a restatement of the first one. It's a completely different requirement (about display not parsing). If possible, please split these two requirements up.