Naming Ordered Sets (Rows)

The first statement of a row within a piece is called the prime form (P) of the row.  Notice what happens to a row’s intervals when the row is transformed by inversion (I), retrograde (R), and retrograde inversion (RI):

                                    Direction                 Order

                   I                  flipped                     same

                  R                 flipped                     reverse

                  RI                 same                      reverse

 

A row’s intervallic pattern can be built starting on any pitch class (pc).  We identify that pc using a subscript: P5 is the prime form of the row starting on pc 5.  The note on which the row is built, the referential pitch class, moves to the end for both the R and RI forms of the row!  Use the last note’s pitch class number as the subscript for R and RI forms of the row.