petroleum engineering software products are often highly complex packages with a wide variety of functions. Users must have confidence in these software tools, must fully understand how their data are being modeled, and must have access to timely advice on how best to apply and use these products. As software packages become more complex, there are greater chances of user error, programming error, or misapplication producing an erroneous result. Software venders must provide users with efficient, reliable tools and adequate training so that they can perform their jobs effectively.