Errors — Stamps that have some major, consistent, unintentional deviation from the normal are considered errors. Errors include, but are not limited to, missing or wrong colors, wrong paper, wrong watermarks, inverted centers or frames on multicolor printing, inverted or missing surcharges or overprints, double impressions, missing perforations, unintentionally omitted tagging and others. Factually wrong or misspelled information, if it appears on all examples of a stamp, are not considered errors in the true sense of the word. They are errors of design. Inconsistent or randomly appearing items, such as misperfs or color shifts, are classified as freaks.