Clearance identifier is a character string managed by a carrier. A code is a character string of letters, numbers, special characters (except escape sequences), and symbols. A date time identifies a date and time of day to various common resolutions: year, month, week, day, hour, minute, second, and fraction of second. The IATA_PayloadStdAttributes defines the standard attributes that appear on the root element for all IATA payloads. Identifies the alternate language for a customer or message. The human language is identified by ISO 639 codes. Allow end-to-end correlation of log messages with the corresponding Web service message throughout the processing of the Web service message. A reference for additional message identification, assigned by the requesting host system. When a request message includes an echo token the corresponding response message MUST include an echo token with an identical value. Identifies the primary language preference for the message. The human language is identified by ISO 639 codes. When true, indicates the message is being re-sent after a failure. It is recommended that this attribute is used (i.e., set to true) only when a message is retransmitted. Used to identify the sequence number of the transaction as assigned by the sending system; allows for an application to process messages in a certain order or to request a resynchronization of messages in the event that a system has been off-line and needs to retrieve messages that were missed. Indicates the creation date and time of the message in UTC. A 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). This indicates where this message falls within a sequence of messages. For all IATA versioned messages, the version of the message is indicated by a decimal value. An identifier is a character string used to uniquely identify one instance of an object within an identification scheme that is managed by an agency. An indicator is a list of two mutually exclusive Boolean values that express the only possible states of a property. A mathematical number that is assigned or is determined by calculation. Text is a character string such as a finite set of characters generally in the form of words of a language.