How to map multiple fileds in a document to the same filed in a documentlist ?
I need a solution without using indices
Do you want to concatenate or map one of the fields based on condition?
Using indexed will only work if you map single fields to a list anyway (beside the examples mentioned below).
If you want to cocatenate you can use a concatenate step or a static expression with the single vars, like %var1%%var2%… (Though not easy to read afterwards). But to be honest, my preferred solutions are pub.string:makeString or pub.string:messageFormat with indexes, as they provide the best readability and are not limited to a fixes amount of inputs.
If you want to map one of the fields only, you need either several branch steps with single mappings or a copy condition to every mapped line (There a different opinions which approach is better programming style 
).
Alls solutions are documented in the Developers Guide respectively the Build In Services Guide.
Regards
Martin
You can also look for copy condition if ur mapping is based on some conditions …