Gum Mistake: printers term for a deviation caused by a gum mistake
Gum Colour Error: deviation from the intended gum colour caused by a mistake
Design Print on Reverse: postage stamp with design print on reverse instead on front
Missing Gum: postage stamp without gum caused by a mistake
Vertical Instead of Horizontal Ribbed Gum: postage stamp with 90 degrees rotated ribbed gum
Horizontal Instead of Vertical Ribbed Gum: postage stamp with 90 degrees rotated ribbed gum
Bark Gum: unregular thick and grazed gum
Streak Gum: uneven put on gum with stripes or small gum-free areas
Gum With Alien Element: during the production mistaken included alien element