An accelerator table contains an array of accelerators. Accelerator tables exist at two levels within the operating system: a single accelerator table for the system queue and individual accelerator tables for application windows. Accelerators in the system queue apply to all applications-for example, the F1 key always generates a WM_HELP message. Having accelerators for individual application windows ensures that an application can define its own accelerators without interfering with other applications. An accelerator for an application window can override the accelerator in the system queue. An application can modify both its own accelerator table and the system's accelerator table.

The application can set and query the accelerator table for a specific window or for the entire system. For example, an application can query the system accelerator table, copy it, modify the copied data structures; and then, use the modified copy to set the system accelerator table. An application also can modify its window's accelerator table at run time to respond more appropriately to the current environment.

Note: An application that modifies any accelerator table other than its own should maintain the original accelerator table; and, before terminating, restore that table.