# FSOverlayID, FS_OVERLAY_ID, FS_EXTERN_OVERLAY

## Definition

  `#include <nitro/fs.h>`
  `

      typedef u32 FSOverlayID;
      #define  FS_EXTERN_OVERLAY(name)   extern u32 SDK_OVERLAY_ ## name ## _ID[1]
      #define  FS_OVERLAY_ID(name)       ((u32)&(SDK_OVERLAY_ ## name ## _ID))

  `

## Description

This function defines the module ID of the overlay that is specified by the `FS_LoadOverlay` function and by the `FS_UnloadOverlay` function. This is generated at link time by `makerom`. The program side can use it as shown below.
Use a `.lsf` file to specify an overlay.
For Example
Overlay overlay_1 After main Object func_1.0 Use a macro in a program to declare an overlay ID.
For Example
FS_EXTERN_OVERLAY(overlay_1); Specify an overlay ID in the `FS_LoadOverlay` function or the `FS_UnloadOverlay` function.
For Example
FS_LoadOverlay(MI_PROCESSOR_ARM9, FS_OVERLAY_ID(overlay_1));
Or
`FSOverlayID id = FS_OVERLAY_ID(overlay_1); FS_LoadOverlay(MI_PROCESSOR_ARM9, id);`

## See Also

`FS_LoadOverlay`, `FS_UnloadOverlay`

## Revision History

06/02/2005 Changed & to &.
11/02/2004 Corrected the structure definition to match the header file.
09/24/2004 Fixed links.
04/08/2004 Revised description due to changes in the `FSOverlayID` type.
04/05/2004 Initial version.

CONFIDENTIAL