Some time ago, I wrote some code to handle colliding date ranges inside a collection. As simple as it may seem, it's not as straight forward as some may think. At that time I used some active objects features and worked very well and contemplated many different scenarios. Since then, I thought about doing the same for CSLA classes, this time in a reusable way. So, here we go:     What cases does this cover? -Two single items inside a collection can't have an overlapping date range (start/end dates). -Items may or may nor be groupped (we'll come back to this later). What does this mean? Well,...