To avoid complex explanations in the large previous lesson covering Documents, we have decided to discuss all the theoretical issues here in an individual lesson. Here we will pay attention to the issues we have omitted or only briefly covered earlier.

This theory is very important for understanding why we use the specific approaches described in the previous lessons. This information is vital for those readers who are willing to develop configurations themselves in the future.

But if you find this section too complicated, you can skip it and return here later. This will in no way damage the development of the training configuration that we discuss in this book.