Cartesian concept
Else clues• *3-D graph line
• 3-D coordinate
• 3-D reference provider
• Depth finder?
• Geometric reference
• Graph line in 3-D
• Graph line in the third dimension
• It's perpendicular to the x-y plane (8th)
• Line in a 3-D system
• Line through the origin in spherical coordinates
• Plot line?