I am reading rules for IUPAC Nomenclature. The following statement is from my book.
Prefixes di, tri, tetra, etc., are not considered in deciding alphabetical order for simple substituents but considered for complex substituents.
With respect to the above statement, what does a simple or a complex substituent mean? Could you please give any examples of simple and complex substituents. How to decide whether a substituent is simple or complex? Is there any rule to decide that?