The layout (A standalone WAM layout or a Layout weblet based WAM layout) is a key element in the generated webroutine presentation. It ensures that a consistent interface is available across webroutines.
When you view your webroutine in the LANSA Editor's Outline tab, the layout weblet is generally at the highest level in the outline tree. This indicates that all weblets below the layout in the tree can refer to the documents specified in the layout weblet.
Some of the things controlled by layouts include:
Of course if you define your own layout, you can decide what common elements need to be included in the interface.