Situation: How do I provide a constant to a target field?
The <C> within the green box indicates that the 'L1' value is a constant. To create a constant within a data mapper:
1) Right click within the mapping rules box
2) Select Constants
3) Double click on the green box that appears
4) Within the "Constant Value Dialog" box, fill in the "Constant Value" field with L1
5) Check the Add Quotes option
6) Click OK
7) Now you can map the constant to the target field.