OPC 10000-1, OPC Unified Architecture – Part 1: Overview and Concepts
http://www.opcfoundation.org/UA/Part1/
OPC 10000-2, OPC Unified Architecture - Part 2: Security Model
http://www.opcfoundation.org/UA/Part2/
OPC 10000-3, OPC Unified Architecture - Part 3: Address Space Model
http://www.opcfoundation.org/UA/Part3/
OPC 10000-4, OPC Unified Architecture - Part 4: Services
http://www.opcfoundation.org/UA/Part4/
OPC 10000-5, OPC Unified Architecture - Part 5: Information Model
http://www.opcfoundation.org/UA/Part5/
OPC 10000-6, OPC Unified Architecture - Part 6: Mappings
http://www.opcfoundation.org/UA/Part6/
OPC 10000-7, OPC Unified Architecture - Part 7: Profiles
http://www.opcfoundation.org/UA/Part7/
OPC 10000-100, OPC Unified Architecture - Part 100: Devices
http://www.opcfoundation.org/UA/Part100/
OPC 40001-1, OPC Unified Architecture for Machinery
http://www.opcfoundation.org/UA/Machinery/