Syntax:     bf(%token-class) tt(classname) 

This directive is only processed when the tt(token-path) directive or option
has also been specified. 

tt(Classname) defines the name of the tt(Tokens) class that is defined when
the tt(token-path) option (see below) is specified. By default the class name
tt(Tokens) is used. Assuming the default, then classes that need access to the
tokens defined by bic() may derive from tt(Tokens) (in which case a token like
tt(IDENTIFIER) can directly be used, or tokens must be provided with their
class context (e.g., tt(Tokens::IDENTIFIER)). The enumeration tt(Tokens_) in
the tt(Tokens) class has public access rights.