The HealthShare documentation is not on docs.intersystems.com, so you can't use Google. In HS Core 15, open the documentation, then click on "Roadmap to Implementing an Information Exchange", then click on Chapter 6, "Supported APIs". Before the name change, the book was called "Roadmap to Implementing a HealthShare Regional Solution" and the supported APIs were in Section 5.5. Searching for "Supported APIs" should also work.