ISE
Setting the Top Module
An ISE® project has one top module
that is the root of the design hierarchy for the purpose of implementation.
The top module is indicated by the top module icon 
in the Hierarchy pane
of the Design panel. You can change the top module for your project
as follows.
in the Hierarchy pane
of the Design panel. You can change the top module for your project
as follows.Note Setting a lower-level module as the top module
allows you to implement only a portion of the design.
To Set the Top Module
- In the Design
panel, select Implementation from the
drop-down list.
- In the Hierarchy pane, select the source file with the module to set as the top module.
- Select Source > Set as Top Module, or click the Set Module as Top toolbar button .
After you set the top module, the top module icon appears next to the
module in the Hierarchy pane, and the hierarchy changes to indicate
that the module is the root of the design hierarchy. You can select
the top module to see all available processes in the Processes pane.
For example, with the top module selected, you can run the Implement
Design process.
appears next to the
module in the Hierarchy pane, and the hierarchy changes to indicate
that the module is the root of the design hierarchy. You can select
the top module to see all available processes in the Processes pane.
For example, with the top module selected, you can run the Implement
Design process.