Characterization Statement

A characterization statement defines a complex field (message or message part) by indicating how other fields can be combined and is similar to a definition statement in BNF. The left side is a complex field name separated (by <-) from the concatenation indications on the right. Field names or equivalent names are concatenated by plus (+), alternatives indicated by slash (/). Slash has precedence over plus so that A + B/C means A followed by either B or C. Alternatives must be distinguishable in their own right.

Characterization statement parts can be grouped in the normal manner by parentheses. (A + B)/C means either A followed by B or C.