UNA segment is to be ignored and that the comma and the dot (".") may be used indifferently in numeric data values. The UNB segment indicates which version of the syntax rules is in effect. Release character (analogous to the \ in regular expressions) is used as a prefix to remove special meaning from the separator, segment termination, and release characters when they are used as plain text ("Escape character" is the equivalent North American term). Segment terminator indicates the end of a message segment. Note: The line breaks after each segment in this example have been added for readability. There are typically no line breaks in EDI data. UNH+1+PAORES:93:1:IA'- This is the message header segment which is required at the start of every message. This code specifies that the message name and version is PAORES 93 revision 1 and it was defined by the organisation IA (IATA). IFT+3+NO MORE FLIGHTS' - This is an "Interactive Free Text" segment containing the text "NO MORE FLIGHTS". UNT+13+1' - This is the message trailer segment. It indicated that the message sent contains 13 segments. Structure EDIFACT has a hierarchical structure where the top level is referred to as an interchange, and lower levels contain multiple messages which consist of segments, which in turn consist of composites. The final iteration is an element which is derived from the United Nations Trade Data Element Directory (UNTDED); these are normalized throughout the EDIFACT standard. A group or segment can be mandatory (M) or conditional (C) and can be specified to repeat. For example : - C99 indicates between 0 and 99 repetitions of a segment or group - M99 signifies between 1 and 99 repetitions of a segment or group A group, like a message, is a sequence of segments or groups. The first segment or group beneath a group must be mandatory, and the group should be made conditional if the logic of the situation demands it. |_Service String Advice UNA Optional |Interchange Header UNB Mandatory : |___Functional Group Header UNG Conditional : : |___Message Header UNH Mandatory : : : |__ User Data Segments As required : : |__ Message Trailer UNT Mandatory : |__ Functional Group Trailer UNE Conditional |___ Interchange Trailer UNZ Mandatory See also Electronic Data Interchange GS1 EANCOM X12 EDIFACT Mapping ASC X12 XML/EDIFACT References External links UN/EDIFACT Main Page - Welcome and News Page 2011-Present - Trade -