Peter B. Hirtle:
"When an author publishes a book or a paper, many publishers ask the author to transfer all copyrights in the work to the publisher. But that is not always to the author's advantage.
Until recently, the primary method that authors could use to retain some rights in their writings was to rewrite the contract with the publishers themselves. Thanks to the development of standardized author addenda, the task has become much simpler. An author's addendum is a standardized legal instrument that modifies the publisher's agreement and allows the author to keep key rights." (http://www.dlib.org/dlib/november06/hirtle/11hirtle.html)
Peter B. Hirtle:
"The addenda usually spells out what rights the author does or does not have in several key areas:
- The extent of the author's ability to continue to use the copyrighted work even after the transfer of copyright to a publisher, including the ability of the author to make copies of the work or prepare new works based on the copyrighted work.
- The author's ability to authorize others to use the work.
- Whether and when the author's institution can make any use of the work.
- Whether and when the author's funding agency can make use of the work.
- When and under what circumstances, if any, people at other institutions can use the work.
- What legal protections are available to the author.
Three different organizations – MIT , Science Commons (through its Scholar's Copyright project), and SPARC – have worked with lawyers to develop self-sufficient addenda that address these issues. These addenda can be attached to the publishing contracts received by publishers and are likely to be legally binding." (http://www.dlib.org/dlib/november06/hirtle/11hirtle.html)
The five addenda are listed and compared at http://www.dlib.org/dlib/november06/hirtle/11hirtle.html