Introspection for references

Hi, This was brought up in the thread for the typed properties RFC, but I'd like to split off this discussion. Before talking about solutions, can the people who need this first outline what functionality is needed and what it is needed for (and maybe what workarounds you currently use). E.g. do you only need to know whether something is a reference, or do you need to know whether two somethings are part of the same reference, etc. There are probably multiple use cases for this with different needs. Regards, Nikita