You can set use customfield type parent to bind multiple child customfields into a parental bundle.

For example for books, you may wish to always give the following description:

Reading level: Ages 9-12
Hardcover: 224 pages
Publisher: Amulet Books (November 15, 2011)
Language: English
ISBN-10: 1419702238
ISBN-13: 978-1419702235

Therefore bind multiple customfields e.g. string into a parent customfield to use it as a pattern.