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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.
9. Coming Attractions, Data Concepts
The following data frames and data elements are still in development in this edition of the standard. They
are not recommended for use in new systems and are presented here for reference because there may be
deployed systems which make use on of them or which depend on them (both in deployments of DSRC and
in other ITS standards). These entries may in turn use definitions taken from other standards that were
taken from the then current adopted standards of these organizations. The referenced standards shall be
consulted for further information regarding their proper use. Unless otherwise noted in each entry, the
below ASN.1 and XML definitions shall be taken as the governing definition when used in this standard,
even when a more current revision of the standard is adopted by the issuing organization. In subsequent
editions of this standard, these entries may not longer be present.
9.1 Message: MSG_CommonSafetyRequest
Use: The Common Safety Request message provides a means by which a vehicle participating in the
exchange of the basic safety message can unicast requests to other vehicles for addition information which
it requires for the safety applications it is actively running. Responding vehicles will (or may) add this
information to the appropriate place in the basic safety message when they broadcast it. Additional
operational concepts are explained further in other clauses of this standard.
Addition information (data elements and data frames) can be requested by this message to be placed into
the Part II sections of the basic safety message (Part I contains selected information that is always present
in every message without exception).
When a device receives a request for a data element it does not understand or support, or from a vehicle
with a spatial position or heading that it may choose to ignore, then that request is simply ignored.
ASN.1 Representation:
CommonSafetyRequest ::= SEQUENCE {
msgID DSRCmsgID,
msgCnt MsgCount OPTIONAL,
id TemporaryID OPTIONAL,
-- Note: Uses the same request as probe management
requests SEQUENCE (SIZE(1..32)) OF RequestedItem,
... -- # LOCAL_CONTENT
}
XML Representation:
<xs:element name="commonSafetyRequest" type="CommonSafetyRequest"/>
<xs:complexType name="CommonSafetyRequest" >
<xs:sequence>
<xs:element name="msgID" type="DSRCmsgID" />
<xs:element name="msgCnt" type="MsgCount" minOccurs="0"/>
<xs:element name="id" type="TemporaryID" minOccurs="0"/>
<!-- Note: Uses the same request as probe management -->
<xs:element name="requests" >
<xs:complexType>
<xs:sequence minOccurs="1" maxOccurs="32">
<xs:element name="request" type="RequestedItem" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="localCommonSafetyRequest" type="local:CommonSafetyRequest"
minOccurs="0"/>
</xs:sequence>
</xs:complexType>