Ships in Star Trek operate on a set of 2 polar cordinates. Imagine 2, 360 degree protractors surrounding a ship. One is fixed horizontally while the other is fixed vertically to the ship. For example, if a heading of 156 mark 213 is given, that means the ship will face 156 degrees along the horizontal axis and 213 degrees vertically.

I removed this from the article as this is a description of the three-dimensional navigational system used in Star Trek, not the guidance system which is a part of the infrastructure of starships. --Jörg 16:20, 27 May 2006 (UTC)
I think we could create an article on "torpedo guidance systems". It would incorporate the "Half a Life" info, as well as info from "Starship Down", "Return to Grace" and "Valiant" to name a few. -- Tough Little Ship 17:01, 27 May 2006 (UTC)
Sure, go ahead! There are enough references of guiding systems that would merit splitting up the article. --Jörg 17:10, 27 May 2006 (UTC)