Certifications are valid for three years.  Professionals may choose to recertify at the same level of competency or apply for certification at a higher level of competency.  Maintaining a level of understanding of current practices in the technical area and gaining on-going relevant work experience are important to maintain competency.  Therefore, requirements for recertification include attending training to maintain and increase knowledge and skills, providing work products to show evidence of competence, and providing references who can attest to work experience and professional ethics.