Skip to main content

Conditional Fields

Within a characterization statement a field may or may not occur depending on the contents of some other previous field. This situation is indicated by assigning a label to the determining field. The conditional occurrence is then indicated by enclosing a condition expression and the optional field description in brackets ([ and ]). For example:

     SS <- V:F1 + CPAIR + [V = C1 > PPAIRS]

which defines a format of 2 and perhaps 3 fields.

  1. Field F1 labeled V followed by
  2. Field CPAIR followed by
  3. Field PPAIRS if the first field (V) was C1; otherwise, this third field is not present in the message.