ok thanks
and since you told me i can not change the name of my duration column, but i want to rename it to "workday duration", i am going to insert the duration2 column and rename it.

how can i make the durations in my new duration 2 column to be the same as my original 5 day calendar based duration column? i will hide the original column from view and just show the workday duration and calendar day duration columns, although i will still enter my values to the duration column in the background.