belongs to: namespace branch in main repo
i just had the idea that we maybe want NAMESPACE to be a list of namespaces (not just one).
one application of that is sharing group items between namespaces (and also other common things). it is somehow similar to NAME being a list, so NAMESPACES could be also a list also.
If more than one name and more than one namespace is present in same metadata, it would mean that ALL names given are present in ALL namespaces given.