While lab testing MDIS-only OPCUA client applications, it was determined that certain facets included from the base spec imposed mandatory functionalities that would not be required in client that is purposed build for MDIS servers. These facets included “AddressSpace Lookup Client Facet” which specified mandatory CU “View Client Basic Browse” and also facet DataChange Subscriber Client Facet which specified mandatory CU “Monitor Client by Index”. The proposed correction is to remove reference to these two facets and instead list the individual CU comprising the facets, denoting mandatory only those that should apply to MDIS-only clients.