+ /** Get the character of tokens that were constructed from a single
+ * character input or a two character input and cat_ == catEscape.
+ * FIXME: The intended usage is not clear. The Token class in
+ * ../mathed/MathParser.cpp (which is the anchestor of this
+ * class) uses a separate char member for this method. I
+ * believe that the intended usage is to not cover tokens with
+ * catEscape, e.g. \code
+ * return (cs_.empty() || cat_ == catEscape) ? 0 : cs_[0];
+ * \endcode
+ * All usages of this method should be checked. gb 2011-01-05
+ */