| Comments | Comments about the order. |
| Orders | A collection of orders with high level information pertaining to the orders.Provides the details of one or more orders. |
| PaymentInformation | Payment information for the purchaser of the order.Details of payment. |
| POS | Point of Sale identification that identifies the source (system and/or person) taking the order and is used for message authentication. Terminal, entity, position, channel information and message password may be included.Point of Sale (POS) identifies the party or connection channel making the request. |
| PurchaserInfo | Contact and loyalty information for the purchaser of the order(s). |
| RecipientInfos | Contact and/or reservation information pertaining to a recipient of the purchased item, it different from the purchaser.Information about one or more recipients. |
| TPA_Extensions | A placeholder in the schema to allow for additional elements and attributes to be included per Trading Partner Agreement (TPA).Allows extensions to be added to the OpenTravel specification per trading partner agreement. |
| UniqueID | An identifier that may be used to reference the item being sold.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). |
| 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. |