-generally) a Laurent series. Similar to most conventional Computer
-Algebra Systems, no distinction is made between those two. There is a
-class of its own for storing such series as well as a class for storing
-the order of the series. A sample program could read:
+generally) a Laurent series. As in most conventional Computer Algebra
+Systems, no distinction is made between those two. There is a class of
+its own for storing such series as well as a class for storing the order
+of the series. As a consequence, if you want to work with series,
+i.e. multiply two series, you need to call the method @code{ex::series}
+again to convert it to a series object with the usual structure
+(expansion plus order term). A sample application from special
+relativity could read: