The most important way that a collection can conform to a collection type is in its size. That is, a collection type describes the size limitations on any collection conforming to it. In the following table, each instance of the collection type Publisher-of-book describes the collection of publishers of a particular book. A typical instance of this collection type is "Publisher-of-Inside-OLE." In the table, each book has only one publisher.
The collection type can define this restriction. That is, the Publisher-of-book collection type can impose on each collection conforming to it a maximum size of one. Similarly, the collection type can define a minimum-size restriction.
The following list contains some other examples:
The minimum size is zero because not every book has a publisher. The maximum size is one because no book can have two or more publishers.
The minimum size is zero because a publisher can exist before it actually publishes any books. The maximum size is "many" because some publishers can publish more than one book.
The minimum size is zero because not every person is an author. The maximum size is "many" because some people can write more than one book.
The minimum size is zero because the authors of some books are anonymous. The maximum size is many because more than one person can co-author a book.