A symbol or token is called terminal when it appears in the resulting formal language.
Terminal Symbol are the characters of the alphabet that appear in the strings generated by the grammar.
In context-free grammars, terminal symbols never appear on the left hand side of a production rule
If a token is terminal, it's therefore not a nonterminal token
White space characters are used to delimit lexical tokens, where required. It is otherwise insignificant.
White space may be a set of characters defined as: