-// Create a symbol for replacing the expression "e" (or return a previously
-// assigned symbol). The symbol is appended to sym_list and returned, the
-// expression is appended to repl_list.
+/*
+ * Note: The internal normal() functions (= basic::normal() and overloaded
+ * functions) all return lists of the form {numerator, denominator}. This
+ * is to get around mul::eval()'s automatic expansion of numeric coefficients.
+ * E.g. (a+b)/3 is automatically converted to a/3+b/3 but we want to keep
+ * the information that (a+b) is the numerator and 3 is the denominator.
+ */
+
+/** Create a symbol for replacing the expression "e" (or return a previously
+ * assigned symbol). The symbol is appended to sym_list and returned, the
+ * expression is appended to repl_list.
+ * @see ex::normal */