An "error" is philately
usually refers something that has gone wrong in the production of a
stamp: the wrong or missing colors, misperforations, inversions, and
things like that. Such errors are relatively rare and therefore
stamps with such errors are expensive. However, there is another class of errors that are not so
rare nor so expensive. They are design errors. In the case of map
stamps they include incorrect coordinates, mistakes in spelling,
incorrect geography, political and historical errors, and other similar matters. This section is concerned with those errors.
The American Topical Association Association includes
“Design Errors” with “ghosts” under “Oddities” in the section
titled “Unplanned Varieties (EFOs)” in their publication,
Elements for Thematic Exhibits.