FPA Transactional Functions

This Section covers the second half of the FPA count: Transactional Functions. These are the active processes (EIs, EOs, and EQs) that move data across the application's boundary, representing user interactions that create, update, or retrieve information. They are the 'actions' that a user performs on the system's data. These functions are typically identified from user stories, use cases, and functional specifications. The focus is on the data that enters or leaves the system, and the processes that handle this data. These functions are what users directly interact with and what deliver immediate, visible results, making their accurate identification and classification paramount to a correct FPA count.

How to Classify & Assign Weights

Complexity Decision Factors

• DETs (Data Element Types): Unique fields or inputs/outputs.
• RETs (Record Element Types): Subgroups within an ILF/EIF.
• FTRs (File Types Referenced): Number of ILFs/EIFs used by a transaction.

Standard Weight Table

Component	Low	Average	High
EI	3	4	6
EO	4	5	7
EQ	3	4	6
ILF	7	10	15
EIF	5	7	10

Classification Rules Summary

• For EI/EO/EQ:
  • Low: ≤ 4 DETs & ≤ 1 FTR
  • Average: 5–15 DETs & ≤ 2 FTRs
  • High: > 15 DETs or > 2 FTRs
• For ILF/EIF:
  • Low: ≤ 19 DETs & ≤ 1 RET
  • Average: 20–50 DETs or 2–5 RETs
  • High: > 50 DETs or > 5 RETs

External Input (EI), External Output (EO), and External Inquiry (EQ)

An **EI** is a function that processes data or control information that comes from outside the application's boundary to inside (e.g., a user submitting a form to create a new customer, a login process, or importing a data file). The key is that it maintains one or more ILFs. An **EO** is a function that sends data or control information outside the application's boundary that includes processing logic to create derived data (e.g., generating a sales report with calculated totals, printing an invoice, or sending a confirmation email after an order is placed). An **EQ** is a function that retrieves data from an ILF or EIF and sends it outside the application's boundary, but it does not change the internal data or contain any processing logic to create derived data (e.g., a user searching for and viewing a product's details, or viewing their order history). The key difference between an EO and an EQ is that an EO performs a calculation or transformation, while an EQ simply retrieves and presents existing data. This processing logic is what makes an EO more complex and gives it a higher weight.

Measuring Complexity with FTRs and DETs

The complexity of a Transactional Function is determined by two factors: **File Types Referenced (FTRs)** and **Data Element Types (DETs)**. An **FTR** is an ILF or EIF that is read or maintained by the transaction. For example, a customer registration form (EI) would reference the 'Customer' ILF. A product search (EQ) would reference the 'Product' ILF. The number of FTRs indicates the number of different logical files the transaction interacts with. **DETs** are the unique data fields referenced by the transaction, just as in data functions. For an EI, this would be all the input fields on the form. For an EO or EQ, it would be all the output fields on the report or screen. A transaction that references multiple files and many data elements is naturally more complex than one that references only a single file with a few data elements.

Transactional Function Complexity Matrix

This matrix shows how transactional complexity is determined by the number of File Types Referenced (FTRs) and Data Element Types (DETs). To classify a function, you find the row corresponding to its FTR count and the column for its DET count. The intersection gives you the complexity: Low, Average, or High. This complexity level, along with the function type (EI, EO, or EQ), is used to find the correct weight for the UFP calculation. For example, an EI with 3 FTRs and 10 DETs would be classified as 'Average', giving it a weight of 4. This structured approach removes subjectivity from the process and ensures a consistent counting methodology across the entire system.