An ASC file is a script file created in ActionScript programming language. It contains code that is run on server side Flash Media Server hosting software. ASC file contains scripts that is used to control application events such as loading Flash applications, handling user actions from mouse and keyboard events, play multimedia content and render the application output. Adobe acquired Macromedia Flash that later became part of Adobe Creativity suit as Adobe Flash. It used to save animation files in .swf file format.
ASC File Format - More Information
ASC files are saved as text files that can be opened and edited with Adobe Media Encoder. These are created and saved as text files and can be opened with any text editor such as Microsoft Notepad, Notepad++ and Apple TextEdit. The ASC file is executed by default when Flash Media Server runs and application.