-output. The second, third and fourth bind the corresponding methods to
-this objects and the fifth is a slot for inserting a method for series
-expansion. (If set to @code{NULL} it defaults to simple Taylor
-expansion, which is correct if there are no poles involved. The way
+output. The second binds the corresponding methods as options to this
+object. Options are separated by a dot and can be given in an arbitrary
+order. GiNaC functions understand several more options which
+are always specified as @code{.option(params)}, for example a method
+for series expansion @code{.series_func(cos_series)}. If no series
+expansion method is given, GiNaC defaults to simple Taylor
+expansion, which is correct if there are no poles involved (as is
+the case for the @code{cos} function). The way