An Agent CharacterAnimation (ACA) is a file format used by Microsoft Agent characters which stores character animations. Unlike most Microsoft Agent file formats, it cannot be opened directly. The only way to load an ACA file is by loading an ACF file created for Microsoft Agent 2.0 that references the animation.
Usage
While not directly the character themselves, ACA files contain an animation for the character. They are able to be loaded through an ACF if it requests to load the ACA file associated with a specific animation name. Since each animation is stored in separate ACA files, this allows for the ACF file to load only the specified animations in the script rather than every animation the character has, using less memory.
Structure
ACA files contain all frames in the animation (including mouth frames), the speed of each frame in the animation, any branching logic used in any of the frames, all images used in an animation, and any audio which is used in that animation. However, ACA files do not contain any metadata about the character nor the system tray icon, since that is all stored in the main ACF file. ACA files can also only contain one animation, meaning two animations cannot share an ACA file.
Trivia
Originally, character animations were stored in AAF files, but were switched over to ACA for an unknown reason.
It is unknown how Agent Character Animations would have been decompiled with the Microsoft Agent Decompiler, as the program never received an update after version 1.0.
