See here for a more comprehensive list of unicode characters.
Basically, if you put certain character sequences between the <sp></sp>
“special” tags, you get “special” characters.
*Also note that if you want to render a ``~`` character in the text area of the output, you have surround it with the special tags like this: ``<sp>~</sp>`` -if you don't put it in tags, the ``~`` simply will not show.