United Nations/Electronic Data Interchange for Administration, Commerce and Transport (UN/EDIFACT) is an international standard for electronic data interchange (EDI) developed for the United Nations and approved and published by UNECE, the UN Economic Commission for Europe. In 1987, following the convergence of the UN and US/ANSI syntax proposals, the UN/EDIFACT Syntax Rules were approved as the ISO standard ISO 9735 by the International Organization for Standardization. The EDIFACT standard provides: a set of syntax rules to structure data an interactive exchange protocol (I-EDI) standard messages which allow multi-country and multi-industry exchange The work of maintenance and further development of this standard is done through the United Nations Centre for Trade Facilitation and Electronic Business (UN/CEFACT) under the UN Economic Commission for Europe, in the Finance Domain working group UN CEFACT TBG5. Example See below for an example of an EDIFACT message used to answer a flight ticket (FRA-JFK-MIA) availability request: UNA:+.? ' UNB+IATB:1+6XPPC:ZZ+LHPPC:ZZ+940101:0950+1' UNH+1+PAORES:93:1:IA' MSG+1:45' IFT+3+XYZCOMPANY AVAILABILITY' ERC+A7V:1:AMD' IFT+3+NO MORE FLIGHTS' ODI' TVL+240493:1000::1220+FRA+JFK+DL+400+C' PDI++C:3+Y::3+F::1' APD+74C:0:::6++++++6X' TVL+240493:1740::2030+JFK+MIA+DL+081+C' PDI++C:4' APD+EM2:0:1630::6+++++++DA' UNT+13+1' UNZ+1+1' The UNA segment is optional. If present, it specifies the special characters that are to be used to interpret the remainder of the message. There are six characters following UNA in this order: component data element separator (: in this sample) data element separator (+ in this sample) decimal mark (. in this sample) release character (? in this sample) reserved, must be a space segment terminator (' in this sample) With the exception of the decimal mark (see below), the special characters in the sample UNA segment above are also the default values. The component data element separator and data element separator are the "first level" and "second level" separators of data elements within a message segment. Referring to them as + and : for brevity, the + separates top-level or composite data elements, and : separates second-level data elements nested within composite data elements. Trailing empty (or null) data elements and their leading separators are omitted to reduce message size. The decimal mark is used to separate the integer from the fractional part of non-integer numbers. The optional nature of the UNA segment and the initial choice of the comma (",") as the default decimal mark provide a source of common confusion. Versions 1 through 3 of the ISO 9735 syntax rules specify the comma as the default; version 4 states that the decimal mark position in the