The Normalizer transformation returns a generated column ID (GCID) output port for each instance of a multiple-occurring field.
The generated column ID port is an index for the instance of the multiple-occurring data. For example, if a field occurs four times in a source record, the Developer tool returns a value of 1, 2, 3, or 4 in the generated column ID port based on which instance of the multiple-occurring data occurs in the row.