in Predynastic Egypt - Page 12
Figure 7: Serekh of the king NEB-RE [Nebra]
Metropolitan Museum (New York)
The mainstream-authoritative British Museum Dictionary of Ancient Egypt describes a "serekh" as follows:
"The term [serekh] is usually employed to refer to a rectangular frame surmounted by the HORUS falcon, within which the king’s 'Horus name' was written.... This frame seems to have effectively symbolized the domain of Horus, the royal residence [as in Figure 7 above]. For a brief period, in the 2nd Dynasty... SETH replaced Horus as the god surmounting the serekh [for the kings Peribsen and Khasekhemwy], thus transforming it into a 'Seth name', but the change was short lived...." 
As we explain in great detail later, this short-term replacement of HORUS through SETH is of enormous importance for understanding and interpreting the Horus and Seth names of the Pharaohs as astronomy.
The Egyptologists think that the lower part of the serekh represents a stylized palace facade. In this regard, the Newby Palette of the Double Falcon shows that this "enclosure" was first found above the falcon and thus could not originally have represented a palace on earth.
Rather, the Pharaohs seem to have viewed heaven’s center as a fenced-in "area of the pole star", which was then subsequently used as the insignia for the name of the king.
Furthermore, we suspect that the Egyptian word serekh is related to the Indo-European root term *ser- "protect" as found e.g. in Latvian sarg- "protect, guard" and German Sarg "coffin, protection of the body". The center of heaven was thus seen as a zone protected by the falcon(s).
 Serekh, Ian Shaw & Paul Nicholson, British Museum Dictionary of Ancient Egypt, British Museum Press, 1995, p. 261.
 See also in German, Horus-Name, "In dem oberen Teil eines sog. Serech (stilisierte Palastfassade...) steht der Horus-Name des Pharaos. Der untere Teil repräsentiert die Palastfassade. Oberhalb des Serechs befindet sich der Horusfalke mit den entsprechenden königlichen Attributen (Verbindung Pharao/Horus). Statt des Horus-Falken kann auch das (mythische) Seth-Tier oberhalb des Serechs erscheinen, wie z.B. bei Peribsen (Seth-Name), einem König der 2. Dynastie.... Ein anderer König derselben Dynastie führt sowohl den Horus-Falken als auch das Seth-Tier auf dem Serech; sein Horus-Seth-Name lautet 'Chasechemui'...."
 *ser-1, Indo-European Roots.