A basic outline, icon or drawing of an opened door. 

Opened Door Outline

A shop front with glass windows and an opened door.

Shop Front

An oven with a stove on top, and an opened door and gas dials or knobs.

A long limousine with see-through windows, an opened door, and wheels turning.

An opened door in perspective, seen from the top at an angle.

An opened door in perspective in a door frame.