Flex 4 Layout Mechanism

Hi All i am new to flex4 i want to know about the s:layout tag which is written below the Application tag, is this layout applicable to the entire application or the elements below the layout tag.

The layout property is used to specify the layout object used to layout the children in the current class.

You can have multiple layout objects declared in one MXML file. For example your MXML file might be a group with a verticalLayout object and contain another group with a horizontalLayout object.

A layout object only applies to the layout of children of the class that it is assigned to.

An hGroup is exactly the same as a Group with a horizontalLayout object assigned to the layout property. This behaves in a similar way to an HBox from Flex 3.