Overview
ISO/IEC 29881:2010 defines the FiSMA 1.1 functional size measurement (FSM) method for software. FiSMA 1.1 measures the functional size of software from the users’ perspective by assessing Functional User Requirements (FUR). It is a service‑oriented FSM method applicable to all types of software and intended for acquisition, development, use, support, maintenance and audit activities. FiSMA 1.1 produces a repeatable functional size in standardized units that can be used for estimation, contracting, benchmarking and productivity analysis.
Key technical topics and requirements
- Scope and purpose: Measurement scope is determined by the purpose of the FSM instance (e.g., first release, installed package subset). Only Functional User Requirements are counted.
- Service orientation: FiSMA 1.1 is based on services (what the software does) rather than internal processes.
- BFC classes and types: The method defines seven Base Functional Component (BFC) classes - q (interactive navigation/query), i (interactive input), o (non‑interactive output), t (interfaces to other applications), f (interfaces from other applications), d (data storage services), and a (algorithmic/manipulation services). These decompose into 28 BFC types.
- Measurement process: Steps include defining the software boundary, identifying FUR, classifying services into BFCs, applying counting rules, and calculating the functional size unit.
- Counting rules and constraints: FiSMA 1.1 provides counting rules for each BFC type (e.g., how to account for data elements, reading/writing references and operations) and a formal method to derive the functional size.
- Reporting and convertibility: The standard specifies measurement reporting and notes convertibility between FiSMA 1.1 and its predecessor (Experience 2.0 FPA) when source data meet recommended detail levels.
- Normative reference: ISO/IEC 14143‑1:2007 (Functional size measurement concepts) is referenced for core FSM definitions.
Practical applications
- Project estimation & bidding: Use functional size to estimate effort, cost and resource requirements.
- Contracting & procurement: Specify or validate scope and deliverables using standardized functional size units.
- Productivity & benchmarking: Compare productivity across teams, projects or vendors using consistent FSM results.
- Scope and change management: Make scope boundaries explicit and manage change impacts based on counted FUR.
- Quality assurance & audit: Support audits and traceability of requirements-to-size measurements.
Who should use this standard
- Project managers, estimators and procurement officers
- Software developers, architects and maintainers
- Quality assurance and audit teams
- Organizations needing standardized functional sizing for benchmarking, contracting or governance
Related standards
- ISO/IEC 14143‑1:2007 - Functional size measurement: definition of concepts (normative reference for FiSMA 1.1)
Keywords: ISO/IEC 29881:2010, FiSMA 1.1, functional size measurement, FSM, Functional User Requirements, BFC classes, software measurement, functional size units.
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