3 Terms, definitions and conventions

3.3 Abbreviations and symbols

Symbol	Definition
Ctrl	Controller
DA	Data Access
HDA	Historical Data Access
HMI	Human-Machine Interface
IEC	International Electrotechnical Commission
MES	Manufacturing Execution System
PLC	Programmable Logic Controller
SCADA	Supervisory Control And Data Acquisition
UA	Unified Architecture
XML	Extensible Markup Language