IEC 62061:2015 specifies the system architecture and the communication protocol of Wireless networks for Industrial Automation - Process Automation (WIA-PA) that is built on IEEE STD 802.15.4-2011. This second edition cancels and replaces the first edition published in 2011. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: - changed IEEE STD 802.15.4-2006 to IEEE STD 802.15.4-2011 and added common modification for IEEE STD 802.15.4-2011 MAC profile, PHY profile and IEEE STD 802.15.4-2011 related references; - added common modifications for regional adoption and added Annex D and Annex E; - deleted extended MAC management services and added two DLSL management services; - added specific state machines for DLSL and NL; - unified representation of frame format and packet format; - changed format of definition of data types; - added detailed description of technologies for clearer understanding; - provided support for CCA modes 1, 2, and 3. Annex E lists all of the "in-some-country" clauses on differing practices of a less permanent nature relating to the subject of this standard.