How are the progressions structured?

There are common structural and organisational features in the progressions. Within each progression, the largest structural unit is an element. Elements are further divided into sub-elements, which are populated with indicators. The indicators within a sub-element are grouped together to form developmental levels. Where appropriate, the indicators in a sub-element are grouped into subheadings The division of each progression into elements and sub-elements, which are presented as sequences, ensures structural consistency throughout the progressions.