Overview
ISO/IEC 20926:2009 - Software and systems engineering - Software measurement - IFPUG functional size measurement method 2009 - defines the rules, definitions and step-by-step process for applying the IFPUG Function Point Analysis (FPA) method to measure software functional size. The standard is fully conformant with ISO/IEC 14143-1:2007 and is applicable across functional domains. It produces a repeatable functional size expressed in Function Points (FP) that is convertible with prior IFPUG sizing editions.
Key topics and requirements
- Measurement framework: Defines the measurement process and counting scope, including how to establish the software boundary and identify Functional User Requirements.
- Counting components: Covers base functional components such as data functions (Internal Logical Files - ILF, External Interface Files - EIF) and transactional functions (External Inputs - EI, External Outputs - EO, External Inquiries - EQ).
- Detailed measurement steps: Prescribes steps to gather documentation, determine scope and boundary, measure data and transactional functions, and include conversion or enhancement functionality when applicable.
- Complexity and sizing rules: Provides the rules and tables for assessing function complexity, counting Data Element Types (DET), Record Element Types (RET), and Transactional File Types Referenced (FTR) used to compute function point values.
- Output requirements: Specifies calculation, documentation and reporting of the final application function point count, including guidance for recording assumptions and the counting rationale.
- Conformance: Explicitly conforms to ISO/IEC 14143-1:2007, ensuring consistency with international functional size measurement concepts.
Practical applications and users
ISO/IEC 20926:2009 is used to produce objective functional size measures that support:
- Cost and effort estimation - translate Function Points into effort or schedule forecasts using calibrated delivery rates.
- Productivity and quality analysis - normalize metrics across teams, technologies and projects.
- Procurement and vendor evaluation - size packaged applications or proposed deliverables for comparison.
- Project scope and change control - quantify enhancement and conversion scope during maintenance.
- Benchmarking and portfolio management - compare systems and prioritize investments by functional size.
Typical users:
- IFPUG-certified analysts and software measurement specialists
- Project managers, estimators and portfolio managers
- Quality assurance and process improvement teams
- Procurement officers evaluating software packages
Related standards
- ISO/IEC 14143-1:2007 - Functional size measurement concepts (normative reference)
- IFPUG Counting Practices Manual - practical guidance and examples that supplement ISO/IEC 20926:2009
- References within the standard include related software maintenance standards (e.g., ISO/IEC 14764)
Keywords: ISO/IEC 20926:2009, IFPUG functional size measurement, function point analysis, functional size measurement, software measurement, function points, software sizing.
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