Define a protocol for syntax tokens

Is my reading correct, that semantic tokens only add additional information to tokens? Can we trust that the clients will render keywords correctly, if they already have a syntax highlighter (frequently regexp based).

If that's the case, should there be an option to "unset" a type. Just as an example, if you have #ifdefs you could think of giving the LSP server the option of removing syntax coloring from inactive code segments by giving it the token-type None.