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SAE J2735-Draft-Rev29 [issued: 12-11-08]
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This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
3.31 entity type: An abstract type of structure defined in the ITS data register but no longer used. There
are no entity types defined in this standard.
3.32 EtherType: The Ethernet Type field, as defined in RFC 1042, used to indicate the higher layer
protocol above Logical Link Control.
3.33 flashing mode: A mode of operation in which at least one traffic signal indication (but more typically
all signal indication of the entire signalized intersection) in each vehicular signal face of a highway traffic
signal is turned on and off repetitively. Expressed in the terminology of the SPAT message, this is
reflected in the descriptions of signal states of the affected lanes (in that movement) being set to red
flashing.
3.34 full-actuated operation: A type of traffic control signal operation in which all signal phases function
on the basis of actuation.
3.35 functional-area data dictionary (FADD): A data dictionary that is intended to standardize data
element syntax, and semantics, within and among application areas within the same functional area. This
DSRC standard is a FADD.
3.36 ingress: In the context of this standard an egress is a flow of vehicular or other types of traffic
approaching an intersection on one or more of the defined lanes of travel.
3.37 initialization: One of three modes, or states, of operation known as Registration, Initialization, and
Operations which DSRC systems operate in. The Initialization mode is used to establish a direct
connection (link) between two DSRC devices. It is comparable to, but not equivalent to, an IEEE 802.11
association.
3.38 intelligent transportation systems (ITS): Systems that apply modern technology to transportation
problems. Another appropriate meaning of the ITS acronym is integrated transportation systems, which
stressed that ITS systems will often integrate components and users from many domains, both public and
private.
3.39 interoperability: The ability to share information between heterogeneous applications and systems.
3.40 intersection: In the context of this standard an intersection is a nexus where two or more approaches
meet and vehicles and other type users may travel between the connecting links. Typically this is a
signalized intersection when considered by this standard, and as such the modes of allowed travel are
reflected in the signal phases, the geometry of the intersection itself, and the local regulatory environment.
The messages of this standard convey some of this information to the traveling public. Specifically, the
MAP message conveys the relevant the road geometry, while the SPAT message conveys the current signal
indication to allow and control movement in the intersection.
3.41 intersection control beacon: A beacon used only at an intersection to control two or more directions
of travel.
3.42 interval: The part of a signal cycle during which signal indications are stable and do not change. In
the SPAT message the current timing value for the remaining interval time estimate as well as the
anticipated interval for yellow change interval is provided for each lane. Because signal interval times