Electronic Data Interchange
Syntax Levels (UN/EDIFACT)

Syntax levels in UN/EDIFACT specify the use of a set of allowed characters as well as service characters only.  This character is identified by a single character from A to Z, and is indicated by the letter following "UNO", at the fourth position of the value defined by the Syntax Identifier element (0001).  The Syntax Identifier is the first data element of the interchange header (UNB), and, thus, the first data encountered in an interchange.

For example, the value "UNOA" indicates the controlling agency "UNO" and the syntax level "A"; the value "UNOB" indicates the syntax level "B"; etc.