Hierarchical design were mentioned before. To create a hierarchical design you can create the required cell separate and place reference to the cell later in a manual way. However this can be inconvenient. An alternative is the gourp feature:
The group feature will in general move selected shape in a new created cell and place a reference to the new cell in the design, so that the resulting design will not change. In detail there are 4 variants of the group feature:
The flat feature is the opposite of the group feature. Shapes in a referred cell are copied to the current cell and the cell reference is removed. As result the design contents is not changed, but just the cell hierarchie structure. The flat feature let you choose how many levels of hierarchie should be removed. On cell arrays a one level flat will convert a cell reference array to a set of single references. A further flat or a 2 level flat will move the shapes of the referred cell into the current cell.