 POS | Point of Sale Identification. Identification number of the vendor that has made the vehicle availability request and agency number assigned by IATA, ARC, ESRP or TID.Point of Sale (POS) identifies the party or connection channel making the request. |
| UniqueID | A unique identifier by which to reference the reservation. This is typically referred to as a reservation number. Generally used at this level when multiple actions are being made to the reservation.An identifier used to uniquely reference an object in a system (e.g. an airline reservation reference, customer profile reference, booking confirmation number, or a reference to a previous availability quote). |
 VehModifyRQCore | Identifies the common, or core, information associated with the request for the modification of a rental vehicle reservation. |
| VehModifyRQInfo | Identifies the supplemental information associated with the request for the modification of a rental vehicle reservation. |
| AltLangID | The alternate language for a customer or message encoded as ISO 639-3. |
| CorrelationID | Allows end-to-end correlation of log messages with the corresponding Web service message throughout the processing of the Web service message. |
| EchoToken | A reference for additional message identification, assigned by the requesting host system. |
| PrimaryLangID | The primary language preference for the message encoded as ISO 639-3. |
| RetransmissionIndicator | When true, indicates the message is being re-sent after a failure. |
| SequenceNmbr | The sequence number of the transaction assigned by the sending system for ordered message processing or message resynchronization. |
| Target | Test or Production target system indicator. |
| TargetName | The name of the Test or Production system. |
| TimeStamp | ISO 8601 encoded timestamp indicating the creation date and time of the message. |
| TransactionIdentifier | Unique identifier to relate all messages within a transaction (e.g. this would be sent in all request and response messages that are part of an on-going transaction). |
| TransactionStatusCode | This indicates where this message falls within a sequence of messages. |
| Version | The OpenTravel message version indicated by a decimal value. |
| ReqRespVersion | Used to request the version of the payload message desired for the response. |