I did this rereading excercise too - but eventually I think I know what he needs. He has a sorted list of records and he want's to determine what kind of sort was used to sort it.

More precisely he has a definition of a family of sorting functions, and the result of applying one of those functions to some data record. He want's to determine what was that function.

Perhaps he want's an algorithm that given the sorted list would output the definition of the sorting function.