Base Size Unit vs. Function Unit


What is the difference between the Base Size Unit and the Function Unit?

The Function Unit is the overall size measure for the project.  It makes sense to describe a book as a collection of chapters or a building by the number of floors or rooms it contains. The Function Unit allows estimators to describe a system as a group of functional or logical components (function points, modules, objects, or screens).

The Function unit is defined by three components:

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SLIM-Estimate SLIM-DataManager