Notes about the OVLDEF file extension:
Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.
The OVLDEF file type is primarily associated with 'Gestionnaire d'extensions' by Francis Gagné. This program allows you to open a file according to its extension (like Windows) or according to its contents (unlike Windows). It also manages multiple extensions in combination (e.g., .ABC.XYZ). [French site]