A feature of this year's contemporary Christmas stamps is a previously unused level of security printing. On this stamp, a 390-line screen vignette appears as fine microscopic lines between two spokes of the wheels of the pumper. The year "1992" is located on the front cross bar of the pumper. Moreover, metallic green ink was used to print "29 USA." The ink blackens when photocopied or scanned during the color separation process.