Abbreviations

The following table contains a list of abbreviations used throughout this document.

Table 1. Abbreviations
Abbreviation	Description
CA	Certificate Authority
CLSID	Class Identifier is a 128bit unique identifier (GUID) that identifies a COM component
COM	Component Object Model
DCOM	Distributed Component Object Model
DCS	Distributed Control System
DHCP	Dynamic Host Configuration Protocol
DNS	Domain Name System
ERP	Enterprise Resource Planning
HMI	Human Machine Interface
LAN	Local Area Network
MES	Manufacturing Execution System
OpenSSL	Open Source implementation of SSL / TSL
PGP	Pretty Good Privacy – cryptography program
PLC	Programmable Logic Controller
Port	TCP protocol uses port numbers to identify application endpoints on a host computer (socket)
ProgID	Associated with CLSID, machine readable identifier for COM component
SCADA	Supervisory Control and Data Acquisition
SOA	Service Oriented Architecture
SSL	Secure Sockets Layer
TCP	Transmission Control Protocol
TSL	Transport Layer Security
URI	Uniform resource identifier
VA	Validation Authority
VB	Visual Basic Programming language
VLAN	Virtual Local Area Network
VPN	Virtual Private Network
WAN	Wide Area Network
OPC	Open Platform Communications aka. Open Process Connectivity aka. OLE for Process Control
DA	Data Access (OPC)
UA	Unified Architecture (OPC)
AE	Alarms & Events (OPC)
HDA	Historical Data Access (OPC)
OS	Operating System
ms	Milliseconds