How to map the name of the tag and not the number in a mapping rule for a XML choice?

It is not possible to use the name of the field in the mapping for the CHOICE.

There are two possible syntax allowed:

-use the business document field order in the choice field as documented

-use the select syntax:
The syntax is SELECT 2ND for example, to get the second child of the choice.  Changes on the Business-Document outside of the choice will not affect the select statement.
e.g.:
1 times do select 1st
1 times do select 2nd
1 times do select 3rd
1 times do select 4th
1 times do select 21st
...