Terminology Reference

The terms used in the HTG7, as shown in the table below, are an attempt to harmonise the terminology used by a variety of efforts around the world. There are also various acronyms and abbreviations included in HTG7 below the terminology table.

Alternative set A set of alternative designs for meeting the same design goal within one area of the HARTS Reference Model. Each member of the alternative set may be a standard or a bundle. The different designs may provide different features that may be useful for different implementation environments, but they all meet the base requirements defined by the reference architecture.

See "overlap"
Alternative triple solution Another interoperability design for a triple solution.

See "overlap"
Architecture Fundamental concepts or properties of a system in its environment embodied in its elements, relationships, and in the principles of its design and evolution. [ISO/IEC 42010:2011] The inherent complexities of architectures result in them being described using several different viewpoints. Each viewpoint produces a view of the architecture that describes how user services are provided when only considering certain aspects of the complete architecture.
Availability 1. "Ensuring timely and reliable access to and use of information..." [FIPS 199; 44 U.S.C., Sec. 3542]
2. An attribute that indicates the degree to which the HARTS information flow requires timely and reliable access to and use of information.
3. An attribute that indicates the degree to which a HARTS triple solution provides timely and reliable access to and use of information.
Bundle A set of standards that cooperatively fulfil some or all the requirements of one area of the HARTS Reference Model.
Communication profile A partial instantiation of the HARTS Reference Model with standards and/or specifications defined for the SubNet and TransNet Layers and optionally for the Facilities Layer, the Management Plane, and/or the Security Plane.
Communication stack A complete set of communication protocols required to implement an information triple in an interoperable manner. Communication stacks are often described in terms of a reference model such as the OSI Reference Model or the HARTS Reference Model.
Communications View A view of the architecture that identifies one or more ways (i.e., triple solutions) to implement an information flow between a source and a destination (i.e., information triple) using industry standards/specifications. The Communications View also identifies any known issues (e.g., gaps and overlaps) that affect each triple solution.
Confidentiality 1. The degree to which a subsystem needs to preserve "... authorised restrictions on information access and disclosure, including means for protecting personal privacy and proprietary information ..." [FIPS 199; 44 U.S.C., Sec. 3542]
2. An attribute that indicates the degree to which the HARTS information flow requires authorised restrictions on information access and disclosure.
3. An attribute that indicates the degree to which a HARTS triple solution provides authorised restrictions on information access and disclosure.
C-ROADS A platform allowing Member State Authorities and Road Authorities to harmonize deployment of interoperable cross-border C-ITS services for road users within Europe.
Data Plane The portion of the HARTS Reference Model that directly deals with the coding and decoding of messages to be exchanged. This includes the Facilities Layer, the TransNet Layer, and the SubNet Layer.
Data profile A partial instantiation of the HARTS Reference Model with standards and/or specifications defined for the ITS Information Layer and optionally for the Facilities Layer, Management Plane, and/or Security Plane.
Destination The ITS subsystem or terminator to which an information flow is sent.
Facilities Layer The layer in the HARTS Reference Model containing OSI layers 5, 6, and 7 that connects the ITS Information Layer to the TransNet Layer. [adapted from ISO 21217:2014] While the exact contents of this layer may vary based on the standards involved, it generally consists of the definition of dialogs, encoding rules, and any middleware services.
Functional object A package of similar subsystem processes from the Functional View of the architecture that are jointly assigned to one ITS subsystem in the Physical View. Functional objects are the most detailed components of the Physical View and provide a link between the interface-oriented architecture and the deployment-oriented ITS services. Functional objects may reflect processes associated with the Facilities Layer, the ITS Information Layer, the Management Plane, or the Security Plane.
Functional View A view of the architecture that defines the logical processes that must be performed to implement the defined user services as well as the data flows that must occur between the processes.
G5 The ITS-G5 standard as specified in ETSI EN 302 663
Gap An issue that indicates a defined architectural need is not currently fulfilled by the triple solution.
HARTS analysis team The team of all HARTS analysts.
HARTS analyst A subject matter expert, who, working with others, is able to develop the Communications View of the architecture by analysing the triples, proposing appropriate standards-based solutions, identifying issues with the proposed solutions, and proposing recommendations for consideration by the industry.
HARTS architecture team The team that is responsible for developing and maintaining the Functional and Physical Views of the harmonized architecture.
HARTS reference model The communications reference model defined and used by the HARTS effort; it is nearly identical to the ITS Station Architecture defined in ISO 21217, but does not impose the requirements related to defined interfaces between layers.
HARTS Toolset Administrator Team The team that is responsible for developing and maintaining the toolset used by the HARTS team, including the database, website generator, and any other tools.
Information flow Information that is exchanged between ITS subsystems. Information flows and their attributes define interface requirements between physical objects that are envisioned to exist by the reference architecture. The identification of these interfaces forms the basis for much of the on-going standardisation work in the ITS community.
Information triple The combination of an information flow with its associated source and destination.
Integrity 1. "Guarding against improper information modification or destruction, and includes ensuring information non-repudiation and authenticity..." [44 U.S.C., Sec. 3542]
2. An attribute that indicates the degree to which a HARTS information flow requires guarding against improper information modification or destruction.
3. An attribute that indicates the degree to which a HARTS triple solution guards against improper information modification or destruction. The specific definition of each value is the same as listed above.
Intelligent transportation system An information, communication, sensor, and/or control technologies system designed to increase safety, sustainability, efficiency, and/or comfort of surface transport systems.
Interface specification The description of essential functional, performance, and design requirements and constraints at a common boundary between two or more system elements. [IEEE 1220-2005]
Interoperability The ability of two or more systems or components to exchange information and to use of the information that has been exchanged [ISO 24765:2010]
Issue An item that might need to be addressed by the standards community. Issues include gaps and overlaps.
ITS application Instantiation of an ITS service that involves an association of two or more complementary ITS functional objects
ITS application specification The specification of functional, performance, security, data, institutional, and regulatory requirements to the extent necessary to ensure interoperability among ITS subsystems participating in an ITS application.
ITS Information Layer The layer that sits on top of the communication stack and represents the information that is to be exchanged and the rules for exchanging this information to provide end-user functionality. Standards assigned to this layer deal with data, functional, performance, security, institutional, and regulatory requirements. The ITS information layer roughly corresponds to what the OSI Model calls the "application", which sits on top of its 7-layer stack and roughly corresponds to what ISO 21217 calls the "ITS-S application entity".
ITS service Functionality entailing the use of information, communication, sensor, and control technologies that increases the safety, sustainability, efficiency, and/or comfort of a surface transportation system.
Latency A property characterizes the time difference between the time at which the source functional object becomes aware of the data in an information triple and the time at which the destination functional object receives it. Within the context of HARTS documentation, latency includes the time that data may be stored within the source of the information triple as well as any network delays.
M5 The Communications for Land Mobiles M5 standard as specified in ISO 21215.
Management Plane The plane depicted on the left-hand side of the HARTS Reference Model, which represents services related to the operation and maintenance of the communication stack and the device in general. The management plane roughly corresponds to what ISO 21217 calls the "ITS-S management entity". EXAMPLE: This includes configuration information for the various layers in the data plane as well as general device information such as a clock, generic scheduler, etc.
NEXUS The Canadian/US trusted traveller programme.
Non-repudiation A property that none of the entities involved in a communication can deny in all or in part its participation in the communication [ISO 24534-4]
Overlap An issue that indicates that there are two (or more) competing standards (or solutions) to implement an information flow that should perhaps be addressed by the standards community. An overlap is different from an alternative. An alternative provides beneficial options to allow flexibility in implementations while maximizing efficiency in different deployment environments; an overlap results from competing designs and implies increased costs in implementing two solutions with little significant benefit in supporting both. For example, there are a wide variety of SubNet communication alternatives for connecting centre subsystems; the selected alternative is often based on issues such as cost to install/maintain infrastructure. By comparison, the CAM and BSM solutions for fulfilling the "vehicle location and motion" information flow are overlapping; they both provide essentially the same service, but the selection is made based on political boundaries largely due to historic decisions made within different regions of the world. Ideally (i.e., assuming no cost or contention to do so), these should be resolved to a single solution; in practice, they may not be due to a variety of reasons.
Physical object An abstract physical entity contained in the Physical View of the reference architecture.
Physical View A view of the architecture that depicts: 1. Physical objects (i.e., ITS subsystems and terminators) 2. Functional objects required by each ITS subsystem 3. Information flows between physical objects
Profile A partial solution for the HARTS Reference Model. See communication profile and data profile.
Pseudonymity ability of a user to use a resource or service without disclosing its user identity while still being accountable for that use [ISO 24534-4]
Public Key Infrastructure See https://en.wikipedia.org/wiki/Public_key_infrastructure
Reference architecture An abstract architecture where the elements of the architecture provide a template for use when developing architectures for implementations. Implementation architectures may instantiate zero, one or more instances of each of the elements in the reference architecture and may also vary from the reference architecture as needed. A reference architecture can be particularly useful for identifying reusable elements for multiple implementations.
Security Plane The plane depicted on the right-hand side of the HARTS Reference Model and represents services related to securing communications and access to data. The security plane roughly corresponds to what ISO 21217 calls the "ITS-S security entity". EXAMPLE: This includes encryption routines and the digital signing of messages.
Service package A portion of an architecture that conveys one or more high-level approaches to providing one interoperable ITS service. For example, an ITS service might be implemented using a heavily centralized approach or alternatively using heavily decentralized approach. An ITS service package includes all known information triples that might exist to implement the service (e.g., whether centralized or decentralized logic is used) with the identified set of physical objects. As such, some information triples might not be implemented in a deployment depending on which approach the deployment uses; but standardized solutions would be needed for all identified information triples to enable interoperability for the identified approaches.
Service package diagram A diagram that depicts all or part of the Physical View of an ITS service package. Particularly complicated ITS service packages might be broken into multiple diagrams.
Solution A specific set of standards arranged per the HARTS Reference Model
Source The ITS subsystem or terminator from which an information flow originates.
SubNet Layer The layer of the data plane of the HARTS Reference Model that provides connectivity services from one node to another on the same network. The SubNet Layer corresponds to the Physical and Data Link Layers of the OSI Model and Access Layer of the ITS Station Architecture as defined in ISO 21217.
subsystem A physical object that interacts with other physical objects and performs various functions as defined by its contained functional objects. Subsystems are grouped into five classes: Support, Center, Field, Vehicle, and Traveler, as defined in Table 3 below. Multiple subsystems may be combined into a single physical entity within an actual deployment, but when this occurs, the ITS subsystems are typically members of the same class. NOTE: Due to the close correspondence between subsystems and the physical world, the interactions among subsystems are prime candidates for standardisation. A subsystem is roughly equivalent to an ITS Station, but internal interfaces and design do not necessarily conform to the ITS station architecture.
Terminator A physical object that is external to ITS and is not assigned any functionality (i.e., functional objects) by the architecture.
TransNet Layer The layer of the data plane of the HARTS Reference Model that provides end-to-end connectivity to Facilities Layers in remote devices across a potentially complex network. It is roughly equivalent to the Network and Transport Layers of the OSI Model, the Internetwork and Transport Layers of the Internet Protocol Suite, or what ISO 21217 calls the "ITS-S networking and transport layer".
Triple solution Specific set of standards arranged per the HARTS Reference Model that specifies one way in which an information triple might be implemented.
Unlinkability The property that user's transactions are not linked with other transactions of the same user. [ISO/IEC 19286:2018]
WiFi® A registered trademark of the WiFi alliance used to refer to wireless local area networks based on the IEEE 802.11 standards.

ACC Adaptive Cruise Control
ACE Automated Commercial Environment (United States import/export reporting system)
APTA American Public Transportation Association
ARC-IT Architecture Reference for Cooperative and Intelligent Transportation
ARIB Association of Radio Industries and Businesses
ASCII American Standard Code for Information Interchange
ATIS Advanced Traveller Information System
AVL Automated Vehicle Location
AWS Amazon Web Services
BRT Bus Rapid Transit
BSM Basic Safety Message
BSMD Bounded Secured Managed Domain
BTP Basic Transport Protocol
CACC Cooperative Adaptive Cruise Control
CAD Computer-Aided Dispatch
CALM Communications Access for Land Mobiles
CAM Common Awareness Message
CAN Campus Area Network
CAV Connected, Automated Vehicle
CAVI Cooperative and Automated Vehicle Initiative
C-C Centre-to-Centre
CCAM Cooperative, Connected, and Automated Mobility
CCC Conventional Cruise Control
CCMS Cooperative ITS Credentials Management System
CCOD Container/Chassis Operating Data
CCTV Closed-Circuit Television
CEN European Committee for Standardisation
CFR Code of Federal Regulations
C-I Centre-to-Infrastructure
CIA Confidentiality, Integrity and Confidentiality
C-ITS Cooperative Intelligent Transportation Systems
CRL Certificate Revocation List
CSR Common Safety Request message
CV Connected Vehicle
CV Commercial Vehicle
CVAC Commercial Vehicle Administration Center
CVCE Commercial Vehicle Check Equipment
CVISN Commercial Vehicle Information Systems and Networks
CVO Commercial Vehicle Operations
CVOBE Commercial Vehicle OnBoard Equipment
CVRIA Connected Vehicle Reference Implementation Architecture
C-X Centre-to-Anything
DATEX Data Exchange
DDS Data Distribution System
DEMN Decentralised Notification Message
DEN Decentralised Notification
DMS Dynamic Message Sign
DNS Domain Name System
DSRC Dedicated Short Range Communications
DTLS Datagram Transport Layer Security
DVI Digital Visual Interface
EC European Commission
ECO Ecological
EOC Emergency Operations Centre
ETC Electronic Toll Collection
ETSI European Telecommunications Standards Institute
EV Emergency Vehicle
EVAC Emergency Communications and Evacuation
EVOBE Emergency Vehicle OnBoard Equipment
EVP Emergency Vehicle Pre-emption
FAST Free And Secure Trade program of the United States
FCC Federal Communications Commission
FHWA Federal Highways Administration
FIPS Federal Information Processing Standards
FNTP Fast Networking & Transport Layer Protocol
FRAME European ITS Framework Architecture
FRAME-NEXT The next version of the European ITS Framework Architecture
FSP Freight Signal Priority
FTP File Transfer Protocol
GHG Greenhouse Gas
GIS Geographic Information System
GPS Global Positioning System
HAR Highway Advisory Radio
HARTS Harmonised Architecture Reference for Technical Standards
HAZMAT HAZardous MATerial
HDMI High-Definition Multimedia Interface
HIDO Highway Industry Development Organization
HOT High Occupancy Toll
HOV High Occupancy Vehicle
HRI Highway-Rail Intersections
HRM HARTS Reference Model
HTG Harmonisation Task Group
HTTP Hypertext Transfer Protocol
IAB Internet Advisory Board
IBL Intermittent Bus Lane
ICA Intersection Collision Avoidance
ICM Integrated Corridor Management
ICMP Internet Control Message Protocol
ICT Information and Communications Technology
ID Identifier
IEC International Electrotechnical Commission
IEEE Institute of Electrical and Electronic Engineers
IETF Internet Engineering Task Force
I-F Infrastructure-to-Field
I-I Infrastructure-to- Infrastructure
IoT Internet of Things
IPv4 Internet Protocol version 4
IPv6 Internet Protocol version 6
ISIG Intelligent traffic SIGnal system
ISO International Organisation for Standardisation
ISP Information Service Provider
ITE Institute of Transportation Engineers
ITS Intelligent Transportation Systems
IVI In-Vehicle Information
JEITA Japan Electronics and Information Technology Industries Association
JPO Joint Program Office
LAN Local Area Network
LED Light-Emitting Diode
MAN Metropolitan Area Network
MCM Maintenance and Construction Management
MCV Maintenance and Construction Vehicle
MDSS Maintenance Decision Support System
MS Microsoft
NEMA National Electrical Manufacturers Association
NHTSA National Highway Transportation Safety Administration
NIAF National ITS Architecture Framework
NMEA National Marine Electronics Association
NRSC National Radio Systems Committee
NTCIP National Transportation Communications for ITS Protocols
OASIS Organization for the Advancement of Structured Information Standards
OBE Onboard Equipment
OMG Object Management Group
ORDS Object Registration and Discovery Service
OSI Open Systems Interconnect
OVW Oversize Vehicle Warning
PAC Payment Administration Centre
PAN Personal Area Network
PDM Probe Data Management
PIAS Personal Information Access Subsystem
PICS Protocol Implementation Conformance Statement
PID Personal Information Device
PKI Public Key Infrastructure
PPG Privacy Protection Gateway
PSAP Public Safety Answering Point
PT Project Team
PT Public Transport
PTMS Public Transport Management System
PVD Probe Vehicle Data
RAD-IT Regional Architecture Development for Intelligent Transportation
RDC Remote Desktop Connection
RDP Remote Desktop Protocol
RFC Request for Comment
RSE Roadside Equipment
RTCM Radio Technical Commission for Maritime services corrections message
SAE Society of Automotive Engineers
SDO Standards Development Organisation
SE Systems Engineering
SENTRI Secure Electronic Network for Travelers Rapid Inspection United States Customs and Border Inspection Program
SET-IT Systems Engineering Tool for Intelligent Transportation
SM Service Monitor
SME Subject Matter Expert
SNMP Simple Network Management Protocol
SNMPv1 Simple Network Management Protocol version 1
SNMPv3 Simple Network Management Protocol version 3
SP Service Provider
SPaT Signal Phase and Timing
SRM Signal Request Message
SSM Signal Status Message
TAT Toolset Administrator Team
TC Technical Committee
TCA Transportation Certification Australia
TCP Transmission Control Protocol
TIC Transportation Information Center
TLS Transport Layer Security
TMC Traffic Management Centre
TMDD Traffic Management Data Dictionary
TPEG2 Transport Protocol Experts Group, generation 2
TR Technical Report
U.S.C. Code of Laws of the United States of America
UDP User Datagram Protocol
USDOT United States Department of Transportation
US-VISIT United States Visitor and Immigration Status Indicator Technology biometric identity management program
UTC Universal Time, Coordinated
UTMC Urban Traffic Management and Control
VGA Video Graphics Array
V-I Vehicle-to-Infrastructure
VMT Vehicle Miles Traveled
V-V Vehicle-to-Vehicle
V-X Vehicle-to-Anything
W3C World Wide Web Consortium
WAID Wide Area Information Disseminator
WAN Wide Area Network
WAVE Wireless Access in Vehicular Environments
WG Working Group
WSMP WAVE Short Message Protocol