What's up with the ninth chevron?

[NAHTMMM]

Originally Posted by Sa'ar Chasm

The whole dialling system makes very little sense. Generally, the Stargate series has been pretty good with their science (Red Sky being an exception), but they inherited a whole lot of gibberish from the movie. You don't need six points to define a location in three-dimensional space, you only need three, although that assumes you're using some sort of grid pattern not based on random squiggles.

I don't watch the show, but I assume that by "points" you mean "coordinates" or "numbers" or some such.
If you want to justify six coordinates, the values could be (x, y, z, t, energy required, check digit) or some such.