§ 170.315(h)(2) - Direct Project, Edge Protocol, and XDR/XDM

§ 170.202(a)(2) Applicability Statement for Secure Health Transport, Version 1.2, August 2015 (Direct)

§ 170.202(b) XDR and XDM for Direct Messaging Specification, Version 1, March 9, 2011

§ 170.202(d) ONC Implementation Guide for Direct Edge Protocols, Version 1.1, June 25, 2014

§ 170.202(e)(1) Implementation Guide for Delivery Notification in Direct, Version 1.0, June 29, 2012