ISO/IEC TR 25021:2007 defines the set of quality measure elements to be used throughout the software product life cycle for the purpose of Software Product Quality Requirement and Evaluation (SQuaRE). While some quality measure elements can be used as standalone quality measures, their main purpose is to be the building blocks for other SQuaRE measurements as described in ISO/IEC TR 9126-2, ISO/IEC TR 9126-3 and ISO/IEC TR 9126-4. ISO/IEC TR 25021:2007 constitutes the link between ISO/IEC 9126 and the subsequent SQuaRE series of standards.
ISO/IEC TR 25021:2007 contains informative annexes documenting the cross-reference relationship between the quality measure elements and quality measures, characteristics and subcharacteristics defined in ISO/IEC 9126.
The Quality Measurement Division, of which ISO/IEC TR 25021:2007 is a member, also offers examples of quality measures that can be used across the product development life-cycle. These measures are defined in the other documents in the division and correspond to the quality characteristics in a software product quality model such as that described in the future International Standard ISO/IEC 25010 (replacing ISO/IEC 9126-1). ISO/IEC TR 25021:2007 is designed to be used, in particular, with other standards in the SQuaRE series that address quality requirements (ISO/IEC 25030) and product quality evaluation (the future International Standard ISO/IEC 25040).