With accurate real-time navigation information provided by a GPS/INS system, the ability to hit a target becomes limited primarily by inaccurate knowledge of its location. Even though numerous methods can identify the coordinates of a potential target, expressing its position in unambiguous terms had been a problem for decades. Before the advent of GPS, each part of the world had a different map reference that was based on its own Local Datum, which is a local representation of an ellipsoid that was thought to be appropriate for that part of the world. One can imagine the difficulty in determining the absolute target coordinates in a reference system without an accurate absolute definition. One of the first benefits that GPS provided was a method to tie all the maps of the world together in a common frame of reference.
Today, using GPS, one can accurately relate a point on a local map to an absolute reference system. In practical terms, this permits target location and strike functions to be performed in the same absolute coordinate system. Such a system significantly improves targeting accuracy; the small remaining targeting errors are now limited to targeting sensor errors and the variability of GPS errors between the targeting phase and the strike phase. GPS errors are becoming so small that the targeting sensor error will become the dominant remaining error in the future.