The ADL file extension is associated with the DESQview a text mode multitasking program for MS-DOS.
ADL file extension - DESQview file
What is adl file? How to open adl files?
File type specification:
The ADL file extension is related to DESQview which was a text mode multitasking program developed by Quarterdeck Office Systems which enjoyed modest popularity in the late 1980s and early 1990s. Running on top of DOS, it allowed users to run multiple DOS programs concurrently in multiple windows.