Original Article:
http://groups.google.com/group/comp.databases.pick/browse_thread/thread/f6b38301e1a67c10/c6f1f4d5064217f4?pli=1
Article
Many old software included assembly routines called User Exits. While User Exits are not needed any more, there is still some backward compatitiblity issues that need an understanding of the User Exists do.
While most of these are commonly found, some are not.
Warning:Use at your own risk. These are not documented (for the most part) and they are totally unsupported. User exits are also subject to change without notice.
See List