The Summon service indexes a wide range of standard suggested content types for both publisher content as well as your local catalog content.
As content types and definitions are 'by cataloger's judgment' and at an organizational level, these are only high level industry definitions from The Library of Congress'
Type of Record and Bibliographic Level & the
Online Dictionary for Library and Information Science, and other standard dictionaries. During your implementation process you may customize these content types for your catalog or institutional repository (IR) content if you wish, and there is no requirement to use all of them.
The standard content types in CDI are defined in this
spreadsheet.