# Is the punctuation part of the alphabet?

Given a language $L \subseteq \Sigma^*$, (it could be Italian, English, C++ or anything else), should we consider the punctuation (".", ";", "->") as a part of the alphabet $\Sigma$ upon the language is built on or not?

For instance, it's easy to accept the set $\{ w.w^R \mid w \in \Sigma^* \}$ with a deterministic pushdown automaton. But remove the $.$ character as a delimiter, and we need non-determinism to guess where the end of the first string is, and where its reversal starts.