What does DUO stand for?

Daily Update Operation

Datatron Users' Organization

Disk Unseen Object

DOS - Disk Operating System under OS - Operating System

Duckbuster Corp., Manson, IA - Manufacturer code for watercraft hull identification number (USCG)

Duetto - Duet - Music (ROG)

Duodecimo - Book up to 20 centimeters in height

Dupaninan Agta - Language code (ETLW)