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User-oriented information has different levels. The simplest describes how to tell to the computer to use a component. This knowledge is easy to obtain. There exist many development tools that produce needed data automatically in clear and comfortable form.

This information is easy to check. In case the component is used in an incorrect form the compiler reports an error. For instance if a programmer calls a function, he needs to know the name of the function, the type of the return value, the types and the number of formal parameters. If he forgets to write one of the parameters, he gets a compilation error.