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The “Transit Benefi t Messages”, explained in section 4.8.4.3, are another
set of
additional messages offered by the standard.
4.8.6 Data Elements
RIS Part 4 supports all the objects and data elements defined in RIS Part 3. The objects
are 16 bytes and contain data elements of varying lengths. RIS Part 4 utilizes these exact
objects
in their “as read” and “as written” status. “As read” refers to the state of the
object when it is first read from the PICC at the start of a PICC/CID transaction.
Subsequently,
“as written” refers to the state of the object when it is written to the PICC
as a result of the transaction sequence. The ‘as read’ and ‘as written’ status of the
product objects are placed together with other data elements to form the message
structure that is sent from the CID through the agency
computer systems to the RCH.
4.8.7 Message Sequences
Act ion list messages originating from the RCH are responded with confirmation
messages with separate message identifiers by AFC devices when the action directive is
successfully implemented. For example, when a RCH sends the message A715, “Block
a Product”, devices respond with an A416 message, “Product Blocked”, when the action
succeeded.
The standard does not define any other message sequences.
4.8.8 Security Requirements
RIS Part 4 supports transmission level data integrity through the use of MACs
appended to every message. The MAC provides the
RCH with the ability to validate the
authenticity
of transaction messages after they have been forwarded from a CID. The
authenticity c heck is achieved through the secret keys stored only in CIDs and the RCH.
4.8.9 Timing and Routing
RIS Part 4 does not define any timing requirements.
4.8.9 Usability
The information provided in RIS
Part 4 is offered free of charge and can be incorporated
within
UTFS WP4’s efforts in order to facilitate the standardization of the interface
between PICC’s host device and a Regional Clearing House (RCH). The Port Authority
prohibits the licensing or charging of fees for use and development
of any portion of
this Regional Interoperability Standard for Electronic Transit Fare Payments.
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