mapping issue

Hi All,

I have a source structure like this

Source:                                                        Target:

<Root>                                                             records 0:99999

    segmentA 0:1                                                fieldA1

         fieldA1                                                      fieldB1

    segmentB 0:99999                                        fieldB2

        fieldB1 0:1                                                 fieldC1

        fieldB2  0:1                                                fieldC2

        segmentB1 0:10

          fieldB11 (value = A,B,C,D,E)

          fieldB12

the number of records in the flat file is based on the number of segmentB. The feildC1 = fieldB12 when fieldB11 = 'A'. fieldC2 = fieldB12 when field B11 = 'B'.  when there is no fieldB11 has value A, fieldC1 = blank; when fieldB11 = 'A', but there is no fieldB12, fieldC1 = blank. The same logic applies to fieldC2.

Can anyone has an idea on how the mapping logic for fieldC1 and FieldC2 would be?

Thanks a lot!

Meiying