However some projects contain the holy code, which nobody is permitted to change, such forever-true texts are rare to meet. As rule each source code unit is subject to check or to change. Let's use the term "developer" to denote a person who is forced to do this. The creation of a new component is simply the case where the code to modify does not exist.
In contrast to the user a developer implements his decisions in the same unit of the source code. To do appropriate decision he needs the user-oriented information and much more. There exist many different levels of developer-oriented information. We'll consider most important of them.