component
A compound document is composed of multiple documents called components. Each compound document has one component, called the parent document, which is the document that was added to the library. All other components, called child documents, are linked to the parent directly or indirectly (via links in child documents). Most operations work on all components of a compound document. For example, when you check out a compound document, you can check out all components in one operation.
Although the components are linked, each component has its independent identify as well. It has its own access rights and can be operated on independently.