EDIFACT

EDIFACT，行政管理、商務與運輸用電子資料交換是由聯合國管理的數據交換標準，是一個多重工業EDI標準。

EDIFACT: Electronic Data Interchange for Administration, Commerce, and Transport
行政管理、商務與運輸用電子資料交換(EDIFACT)是由聯合國管理的數據交換標準，是一個多重工業EDI標準。
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) and are normalised 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, while M99 signifies between 1 and 99 repetitions.
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 Conditional
+----- 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