If you owned a large, varied music collection ,how might you devise a key to keep track of all your different kinds of music?

A  documentary film  is a nonfictional motion picture intended to document some aspect of reality, primarily for the purposes of instruction, education, or maintaining a historical record.example:     20,000 days on earth

Tan, an pearl. it's unique.

There is now picture how are we supposed to see 

Not 100% sure on the answer but i’d say universal as i don’t see why it would be in the definition