Calculating Time

I have some views that calculate the time difference from when a document was created, to the time it is marked complete - relatively simple. How can I go about capturing this time during certain status of a document cycle as well as not including weekend time? For example, if the request status In Process the “clock” should be running time if the status is waiting, the “clock” should stop. Then return to counting time if the status is set back to In Process. I can tag each start & stop with dates & times, should this date be stored separately then calculated? Additionally how can I exclude weekend time? thanks for any help…

Subject: Calculating Time

Look in the help under @BusinessDays