US Core Implementation Guide, published by HL7 International - Cross-Group Projects. This is not an authorized publication; it is the continuous build for version 6.1.0-snapshot1). This version is based on the current content of https://github.com/HL7/US-Core/ and changes regularly. See the Directory of published versions
This table compares Must Support Elements across all the US Core Observation Profiles.
This table is also available as an Excel file.