Abstract: Plastic, color-coded X-ray marker with a cavity containing mercury. The cavity has deeper central portion and shallower branches, relative to the face of the marker. An X-ray negative shows the mercury in the central portion if the X-ray film was flat when exposed and shows the mercury in one or more branches indicating up and down direction if the X-ray film was upright when exposed. The cavity preferably has an asterisk shape whereby the mercury forms an arrow shape indicating up direction on the negative when the film was upright when exposed. Lead indicia indicated right or left and operator's initials. Markers are secured to film holders by a multiplicity of suction cups.