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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.
3.20 data element: A syntactically formal representation of some single unit of information of interest
(such as a fact, proposition, observation, etc.) with a singular instance value at any point in time, about
some entity of interest (e.g., a person, place, process, property, object, concept, association, state, event). A
data element is considered indivisible.
3.21 data frame: (formerly: Data Structure, which appears in the early ITS efforts, is now more commonly
called a Data Frame. The definition and meaning, which follows, remains the same.): Any construct used
to represent the contents of a Data Dictionary. From a computer science perspective, data frames are
viewed as logical groupings of other data frames and of data elements to describe "structures" or parts of
messages used in this and other standards. A data frame is a collection of one or more other data concepts
in a known ordering. These data concepts may be simple (data elements) or complex (data frames).
3.22 data plane: The communication protocols defined to carry application and management data across
the communications medium.
3.23 data registry: An advanced data dictionary that contains not only data about data elements in terms of
their names, representational forms and usage in applications, but also substantial data about the semantics
or meaning associated with the data elements as concepts that describe or provide information about real or
abstract entities. A data registry may contain abstract data concepts that do not get directly represented as
data elements in any application system, but which help in information interchange and reuse both from the
perspective of human users and for machine-interpretation of data elements. Within the ITS industry, there
is a data registry established and run by the IEEE which contains the contents of this standard. SAE and
the ATIS committee have also developed tools to access and use the data found in the registry as an aid to
deployments.
3.24 data structure: Any construct (including data elements, data frames, and other data concepts) used to
represent the contents of a data dictionary.
3.25 data type: A classification of the collection of letters, digits, and/or symbols used to encode values of
a data element based upon the operations that can be performed on the data element. For example, real,
integer, character string, Boolean, bitstring, etc.
3.26 dialog: A sequence of two or more messages which are exchanged in a known sequence and format
(typically of a request followed by one or more replies), which are considered a bound transactional
exchange between the parties.
3.27 dual-arrow signal section: A type of signal section designed to include both a yellow arrow and a
green arrow.
3.28 egress: In the context of this standard an egress is a flow of vehicular or other types of traffic leaving
an intersection on one or more of the defined lanes of travel.
3.29 encounter: In the context of this standard an encounter is an exchange of messages between two or
more DSRC equipped devices (OBUs or RSUs) lasting for a brief period of time.
3.30 entity: Anything of interest (such as a person, place, process, property, object, concept, association,
state, event, etc.) within a given domain of discourse (in this case within the ITS domain of discourse).