Category:In (relation)

In is a key relation in the ontology of Commons categories, generally represented in the format "topic1 in topic2". Topic1 is the primary topic, while topic2 is the defining topic, meaning that an 'in' category is limited to parts of topic1 which are located within the boundaries of topic2. This makes them generally sub-categories of the equivalent "of" category.
Example: Aircraft in France is a category contianing all Aircraft located within the boundaries of France, and is a sub-category of Aircraft of France.