A #01 file extension is related to a method of numbering photos captured from the camera film.
#01 file extension - Numbered picture
What is #01 file? How to open #01 files?
File type specification:
The #01 file extension is used as a method of numbering photos scanned from camera film.
The #01 file stores picture image, or photo. Other photos from the film are countered as #02, #03, #04...#xx etc.
This #01 file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.