Spotfire: Calculating the Date Differences between Values in the Same Column which are Group by another Column

Question

I am a beginner in Spotfire. I made a sample table which can be seen below. This is what I am trying to accomplish: for each TYPE I want to calculate the difference in days between ACTIVITY 1 START and ACTIVITY 3 FINISH.

I was trying to utilize the function DateDiff but am confused on how to do this since I want to specify the START and FINISH by the value in ACTIVITY. I also believe I will have to use the OVER function.

Sample Table

Answer 1

    #I would write something like : 

    DateDiff("day",Min([Start]) over ([Type]),Max([Finish]) over ([Type]))