Velocity fields and rotation curves (receding side only: red or light grey; approaching side only: blue or dark grey; a combination of both sides: black) of some example galaxies representing five different types of velocity patterns. From top to bottom: UGC 6446 (type 1: receding and approaching sides agree at all radii), UGC 2080 (type 2: receding and approaching sides have a constant offset), UGC 9211 (type 3: receding and approaching sides agree well at small radii, but differ significantly at large radii), UGC 8863 (type 4: receding and approaching sides differ at small radii, but agree well at large radii), UGC 7353 (type 5: the curves of receding and approaching sides change sides).