Total float calculation in P5

Even I thought they are same, but check this out from p6 help menu:

If you base float on start dates, and all activities are assigned to the same calendar, total float is the difference between the earliest late start and the earliest early start dates in workperiods. For finish dates, the Project Management module uses the latest late finish and the latest early finish dates to calculate total float. The most critical float is the lowest total float encountered in the detailed activities from each summary group.

This statement seems to be applicable to a group of activities under a summary group, because Primavera does show total float value for a summary group. I am not sure however if the P5 setting is applicable to summary groups only or to individual activities also.

I am doing a literature review at this time because I do remember seeing the terms ’start float’ and ’finish float’ somewhere.

Here is the answer that I got from US Army Corps of Engineers website (publication# EP 415-1-5 (link is provided below):

"In the Precedence diagramming system, if start to start or finish to finish lags are used, it is possible for the total float on the start and finish of an activity to differ. In such an instance the start float may be more critical (smaller) than the finish float or vice versa."

www.usace.army.mil/usace-docs/eng-pamphlets/ep415-1-4/c-3.pdf

There is an example network schedule provided that explains the above.

Happy reading!

Correction to last post: The publication ID is 415-1-4.