When using the Biztalk mapper, most often than not you would need to resort to functoids. When connecting the functoid inputs from the fields in the Source schema, we simply stretch a line from the field to the functiod. However, when we open the functoid to check the input parameter, it shows up as a long xpath string. When dealing with large maps this can very easily become cumbersome.
Alternatively, a better way is to label the line that you stretch to the functoid. So whenever you draw a line from any source field to the functoid. Just click the line and enter a meanigful name in the Label property in the Properties window. The next time you open the Input Parameters window for the functiod, you will see the line label instead of the cryptic xpath.
This surely will make life a bit easier when dealing with huge maps. Also, this can be one of the good coding practices.