A where a number was accidentally appended.
While "MP4" is a ubiquitous digital multimedia container format (ISO/IEC 14496-14), "56mp4" is a recognized extension of this standard. If you encountered this as a file extension, it may be: A where a number was accidentally appended
: The string frequently appears in OCR (Optical Character Recognition) scans of historical newspapers. In these instances, it is usually a "misreading" by the software of physical characters—such as time notations (e.g., "5:56 PM") or celestial data (sunrises/sets)—printed in old or damaged fonts. A where a number was accidentally appended