Within data load and dimension build rules files, you can join multiple fields into one field (which is given the name of the first field in the join).
Before joining fields, position the fields in the order in which you want to join them.
To join multiple fields into one field:
Select Field, then Join.
In the Join Field dialog box, in the Fields to join list box, select the fields to join.
For example, select field2 and field3 to join them.
Click OK.