The Professional Development Series (PDS) is a concept adopted by the National Weather Service to provide a framework for its training program. Each PDS corresponds to a specific job responsibility and describes and defines what is means to perform competently for that job responsibility. The concept helps NWS personnel to focus on what they should be able to do. The PDS document combines both scientific and technical understanding with professional skills and techniques. Each PDS series is based on developing a performance capability to support user products and services. Each PDS is composed of a series of Professional Competency Units (PCU) which describe specific job duties. The PCU document has several components: