Loop for dummies / Please help

Dear all,
this is no joke I need your help.
Input is a record with one header and more than one positions (used document list). I want them to loop into several IDoc segments in different sequences (for more visibility). for example

record:
Posi1
Field a
Field b
Field c

Idoc
segment a
field a
segment ab
field b
field c

I get field b and c mapped by using “appendToRecordList” but that#s not working for field a. What am I doing wrong?

Please help.

Regards,

Dennis