Glucinated Positioning Sap (short: GPS) is a special type of sap found in GPS Fruit growing on GPS Trees, both named after the sap. It contains Geomancy. If you pour it into a bowl, and then drop an artificial, non-magical battery in it, it will display a map of the area with a compass, but also slowly drain the electricity out of the battery. NEVER try to charge it using Electromancy, as it is very reactive and may explode or, even worse, react like Francium with even more harmful radiation (not ordinary radioactivity but magical radioactivity, even more harmful). It is unknown how it actually works, since we started making maps before we discovered how to use GPS and the maps look almost exactly the same-and the locations get Common Tongue names too.
Some report the sap tastes sweet, which is the cause of the "Glucinated" part in the name. However, it is extremely toxic, so the ones that reported it died shortly after.
Some companies decided to make metal bowls with glass above, with a space for a battery under the liquid but connected with copper wires, so the sap can't accidentally pour out and is more portable. This is sometimes referred to as a "GPS Device".
Not to be confused with the non-magical Glucine Positioning Sap, which can only be used for finding out where the north is.