## 6.4 Other Roles
Apart from the core PM2-Agile Roles described so far, another set of roles may also be part of project’s lifecycle. **Typically**, these other roles join the Agile Project Core Team (A-PCT) **on a temporary basis** and help the team address and overcome specific challenges, **both from a business and technical perspective**.
**Domain Expert**
The Product Owner (PrOw) is regarded as the ‘single voice of the stakeholders’. However, **inviting domain experts**, **such as business analysts for the business domain** that the information system supports, helps the Agile Project Core Team (A-PCT) better understand the overall context and scope of the project.
**Technical Expert**
The Agile Project Core Team (A-PCT) comprises cross-disciplinary skilled individuals who can tackle most of the technical challenges during the project. Yet, for some projects, it **might be useful to have technical experts’ contribution**, even if only **on a temporary basis**. Technical experts possess specialised knowledge and experience in a given software development area and help the Agile Project Core Team (A-PCT) a**ddress and overcome technical challenges**. Specialised areas may include ==software architecture, user experience (UX), security, database administration==, among others. For example, a technical **expert from the Architecture Office** can help the team develop a solution that is **coherent with the overall enterprise architecture**.
**Independent Tester**
Agile Project Core Teams (A-PCT) are responsible for the quality of an iteratively and incrementally delivered solution. Testing of the software is part of the responsibilities of all Agile Team Members (ATeM). Yet, **some organisations require projects’ software to be validated by a quality assurance team**, working in parallel with the Agile Project Core Team (A-PCT).