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A thing is anything that is the subject of a stamp or issue.
Things include animal, plants, people, places, organizations,
historical events, artifacts, symbols, and so forth.
Things appear in StampData as either an element of a design or design type, or else as the occasion of an issue. Common design usages include different species of birds and butterflies, while occasions include birthdays of persons, or the holding of a sports event. Some things may appear indirectly, such as the artist who created the painting depicted on the stamp.
Some things are 'types', meaning that they encompass a number of other things. For instance, 'bird' is a thing type; it is a type of animals, while hummingbirds and parrots are subtypes of birds. The most general and/or unclassifiable things do not have types and are either listed with a blank type, or as type 'other'.
Things may have synonyms, which is simply another name for the same thing. For instance, bird species have a name in English and a scientific name that is a synonym.