- advise
- A request for an asynchronous notification that a period of time has elapsed.
- alpha
- The measure of a pixel's opacity. A pixel with a maximum alpha value is opaque, one with a value of zero is transparent, and one with an intermediate value is translucent.
- application notification
- An event that the application retrieves from the event notification queue.
- asynchronous reader filter
- A file source filter that does no parsing on its own, but simply reads data from a media file.
- ATR
- Audio tape recorder.