Case Studies 1, 2, and 3 present function point counting in the context of different implementations of the same Human Resources application. Each case illustrates function point counting at two points in the development process - at the end of the analysis phase, and at the end of system construction. The information below describes the implementation approaches illustrated by each case.

Case Study 4 presents an implementation of a Traffic Control System. This case study illustrates function point counting of real-time components of an application.

Case 1: Counts Function Points during Analysis and Construction for a Human Resources Application
Basis for Count	Function Types Counted
Analysis counted using User requirements Entity-relationship diagram (Martin base with variations) Hierarchical process model	Data Function Types Internal logical files (ILFs) External interface files (EIFs) Transactional Function Types External inputs (EIs) External outputs (EOs) External inquiries (EQs)
Construction counted using Count from Analysis Updated user requirements DB2 data base Graphical user interface (GUI) windows	Data Function Types Internal logical files (ILFs) External interface files (EIFs) Transactional Function Types External inputs (EIs) External outputs (EOs) External inquiries (EQs)
Case 2: Counts Function Points during Analysis and Construction for a Human Resources Application
Basis for Count	Function Types Counted
Analysis counted using User requirements Entity-relationship diagram (CHEN based with variations) Data flow diagram	Data Function Types Internal logical files (ILFs) External interface files (EIFs) Transactional Function Types External inputs (EIs) External outputs (EOs) External inquiries (EQs)
Construction count using Count from analysis Updated user requirements IMS database Data flow diagrams Common User Access (CUA) screens	Data Function Types Internal logical files (ILFs) External interface files (EIFs) Transactional Function Types External inputs (EIs) External outputs (EOs) External inquiries (EQs)
Case 3: Counts Function Points during Analysis and Construction for a Human Resources Application
Basis for Count	Function Types Counted
Analysis counted using User requirements Object Oriented Class Diagram Use Case Diagrams	Data Function Types Internal logical files (ILFs) External interface files (EIFs) Transactional Function Types External inputs (EIs) External outputs (EOs) External inquiries (EQs)
Construction counted using Count from Analysis Updated user requirements Updated Object Oriented Class Diagram Updated Use Case Diagrams Graphical User Interface (GUI) windows	Data Function Types Internal logical files (ILFs) External interface files (EIFs) Transactional Function Types External inputs (EIs) External outputs (EOs) External inquiries (EQs)
Case Study 4: Counts Function Points for a Traffic Control System with Real Time Components
Basis for Count	Function Types Counted
High-level User Requirements Representation of the City Traffic Light System Boundary Diagram Entities	Data Function Types Internal logical files (ILFs) External interface files (EIFs) Transactional Function Types External inputs (EIs) External outputs (EOs) External inquiries (EQs)