What in particular is your problem with cartouches in general?
As I'm sure you are aware, kings and queens of Egypt also had a Horus name which was written inside a rectangle, representing the enclosure and facade of the royal palace. This was known to the AEs as the 'srh' or 'serekh'.
It was during the middle of the third millennium BCE when the monuments of the rulers begin to place an increasing emphasis on two names written inside loops of rope, known as a 'cartouche'. One of the two cartouche names was assigned to the pharaoh at her or his accession and is unique to her or him. Interestingly, from the 5th dynasty the prenomen of the pharaoh always incorporate the circumpunct, Ra.
It is easy to identify the prenomen because it it will be in a cartouche after the title 'nsw bity', meaning either 'Dual King' or perhaps 'King of Upper and Lower Egypt'.
Also, the fact that the Philae obelisk has the names of "Ptolemaios" and "Kleopatra" in both hieroglyphic and Greek inscriptions strengthens the idea that the cartouche was used for the prenomen or the nomen of a ruler.
Perhaps most importantly is the 'Abydos King List', inscribed as two rows of thirty eight cartouches, naming 76 kings of Ancient Egypt - interestingly, omitting the Armana dynasty and Hapshetsut.
Post Edited (01-Jun-14 19:47)