As you know, Asciidoctor extends way beyond "ASCII". It has full UTF-8 support.
To make your next symbol party a success, here's a new reference website I discovered that shows the entire set of characters defined in unicode. You can browse the symbols by category or search for symbols by name.
http://unicode-table.comIn the spirit of open source, the site drives all updates through a git repository hosted on GitHub.
-Dan