I've been trying to see what special characters are used in Numista by trying to search for them.
Search for a backslash () in general search finds nothing and empties the search string. Searching for two (\) converts the search to a single backslash and finds nothing.
Searching in lettering for a single backslash shows a search for lettering with no content and finds everything.

Searching in lettering for two backslashes is where things get interesting:
