When AF attribute traits were designed, the guiding principle was that traits would be inherent "properties" of the attribute. Specifically the Limits traits were to facilitate easier visualization in our client product such as PI Vision. The use case would be: trend this measurement also the limits so that users wouldn't have to additionally find the limits.
As such, traits have limitations by design as they are not treated the same as regular attributes. For example, there is no concept of attribute references (parent-child, composition, etc.) for traits. This request is to extend this concept to have either child attributes or (child) traits, for existing attribute traits. This request does not follow the original design principle for traits thus we have no plans to implement this request.
