Groups Structure:

Matrix reports are established with four or more groups:

Two or more dimension groups

In  the  layout,  the  information in at least one  groups  goes  across  the  page,  and  the data in at least one group goes down the page, forming a grid. The groups which give the data to be shown across or down the page are known as Dimension Groups.The  information  in  Dimension  groups  is  sometimes  referred  to as  Matrix  labels  as  they give column and row labels for the matrix. The Dimension groups are contained inside the cross product group.