https://build.fhir.org/subscriptions.html#finding-topics suggests re-using topics in https://registry.fhir.org I went there looking for a list of topics, but had trouble finding them, though I did eventually find some.

I'm not sure if this is a feature request to https://registry.fhir.org for better filtering options, or a suggestion to the core spec to better explain how to discover existing topics.  Or maybe the link we have in the core spec includes some default search filters like https://registry.fhir.org/results?latestFilter=true&resourceContextFilter=%22instance%22&resourceFilter=%5B%22SubscriptionTopic%22%5D

I think I ended up finding a few (two examples in R4 and R4 packages, and handful in DSUBm).  But it felt a little odd to such a strong recommendation to re-use existing topics, when there really weren't any existing topics (except DSUBm).   Should we wait until we have at least a handful of topics in the registry before we send folks there?

I don't feel super strongly here, it was just weird to see such a strong recommendation  to reuse topics but then not have anything there to actually reuse.