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In page Cobordism:

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Null-cobordisms with additional structure are called fillings. Bordism and cobordism are used by some authors interchangeably; others distinguish them. When one wishes to distinguish the study of cobordism classes from the study of cobordisms as objects in their own right, one calls the equivalence question bordism of manifolds, and the study of cobordisms as objects cobordisms of manifolds.[citation needed]