What different levels can I export from PlanAhead, and what do they produce?
You can export the entire design by choosing to export the design top level. PlanAhead will export "top.edn" and "top.ucf" files to the directory that you specify.
You can choose to export a physical block created in PlanAhead. PlanAhead exports "pblock_name.edn" and "pblock_name.ucf" files to the directory that you specify.
You can choose to export a logical instance. This can be achieved by selecting an instance from the logical hierarchy and then using the "export IP" menu command.