Naphtha

Techniques Glossary A-PEN (Annealed-Polyethylene Naphthalate)
The base for APS film emulsions.

naphtha
an aliphatic low KB hydrocarbon solvent; any of several volatile hydrocarbon liquids derived chiefly from coal tar, used as a solvent.

Naphtha is a volatile petroleum based solvent such as benzine or gasoline (but not kerosene).
ND is an abbreviation for neutral density.

Annealed polyethylene naphthalate-a polyester material used as the base on Advanced Photo System film; thinner, stronger and flatter than the acetate base traditionally used in consumer photographic roll films.
APO ...

-A-PEN - annealed polyethylene naphthalate. A polyester material used as the base on Advanced Photo System film.
-Aperture - circular hole in the front of the camera lens which controls the amount of light allowed to pass on to the film.

In the 9th century, oil fields were exploited in Baku, Azerbaijan, to produce naphtha.