Chain Of Responsibility is one of the 23 Design Patterns elucidated in the most excellent Gamma And Helm book, Design Patterns: Elements of Reusable Object - Oriented Software by Gamma and Helm et al. ISBN 0201633612 , which is cited below:

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Intent: Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request. Chain the receiving objects and pass the request along the chain until an object handles it.

Design Pattern Classification: Behavioral Object

Applicability:
Use the Chain Of Responsibility pattern when:

• More than one object may handle a request, and the handler isn't known a priori. The handler should be ascertained automatically.
  
• You want to issue a request to one of several objects without specifying the receiver explicitly.
  
• The set of objects that can handle a request should be specified dynamically.
  
• See Also: _ Chain Of Responsibility Discussion

Structure:

A typical object structure might look like this:


See: Andy Kramek's excellent explanation of this pattern.
http://weblogs.foxite.com/andykramek/archive/2006/12/24/3060.aspx

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See Also: VFP Design Pattern Catalog

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Category Design Patterns