As an SDK developer, I must know if a Server supports every DataType definition via the 1.04 DataTypeDefinition or am I forced to read the old DataTypeDictionaries. If one is to read the old DataTypeDictionaries, it basically must be done as part of the connect, since resolving them is a complex action which can block the tcp channel (or server processing capabilities) for a large enough time to cause data loss or delay, depending on how tight publishinterval is.

There is the 'Deprecated' Property of https://reference.opcfoundation.org/Core/Part5/v104/docs/D.5.2, but that is per dictionary. It requires multiple service calls during connect to resolve are all of the deprecated (Browse for the dictionaries itself, then Browse or TranslateBrowsePathsToNodeIds the Property NodeId, then Read). Latency penalty is applied for each call.

Thus, therefore IF possible (maybe this is too late though) I would like to have a single Boolean-DataType'd node below Server or e.g. in ServerCapabilities, that would show would the value for the 'Deprecated' Property of https://reference.opcfoundation.org/Core/Part5/v104/docs/D.5.2 be True for all DataTypeDictionaries. Something like "AllDataTypeDictionariesAreDeprecated" (feel free to invent a better name, I'm not very good with those).

Obviously the node wouldn't exist in anything already out there, but this could serve as an optimization for future clients.