Another thing to note is that the "Merriam-Webster dictionary" suggests that the term "alphanumeric" may often additionally refer to other symbols, such as punctuation and mathematical symbols. This opens up a whole range of other possibilities, and a whole range of other confusions. It is not the usual way the term 'alphanumeric' is used. The "Shorter Oxford English Dictionary" defines the term as given above in our first line (though not quite in the same words).