What does the term ´selected´ mean?

This paper deals with an assumption of the Shannon theory, notably we analyze the possibility of counting n ´selected´ items which is prerequisite to the entropy calculus. We start from the notion, which Shannon provides verbally, we translate it into a formal definition and calculate three cases regarding both analog and digital signals. In such a way we aim at sharpening the applications up and expanding the theoretical coverage of Shannon´s masterpiece over the information and communication technology