I lion stamps. In 1986, the printing of these definitives was taken over by the House of Questa. Questa's stamps included the type II lion symbol, but the stamps were perforated 15 by 14 and are very common. These stamps are different from the Waddington printing, and both are required to complete a specialized collection. A third type of collection, after face-different and specialized, would include errors.
Errors result when some aspect of the production process is accidentally omitted.
Most errors available for the Scottish Machin regionals are stamps that have phosphor bands omitted and stamps with perforations missing. Should a collector strive for completion, he might want to include one example of each error in his collection. Including errors would bring a total collection of Scottish regional Machin definitives to about 200 stamps. Because errors are much scarcer than common stamps, both the time it would take to complete a collection with errors and the amount of money it would cost would increase substantially. Collectors can create their own definition of completeness, and that's part of the fun.