By identifying six constellations in space, a single sextangulation point can be interpolated that corresponds to the destination desired. As only a small portion of the possible combinations of Stargate symbols represent valid addresses, dialing the Gate at random is largely futile. In "Children of the Gods", SG-1 discovers a room on Abydos with a list of valid Stargate addresses and (luckily) a map that allows the SGC to compensate for thousands of years of stellar drift. In the series, the fictional planet Abydos could be dialed because it is relatively close to Earth, although in the film, Abydos was located in the Kaliam Galaxy. It was initially believed that the Goa'uld created the Stargates, but this was proven false in "The Torment of Tantalus" when the SGC discovered that Earth had accidentally dialled an address in 1945 that was not on the Abydos cartouche. Following this revelation, a larger list of Stargate addresses is provided by Jack O'Neill in "The Fifth Race" from knowledge downloaded into his mind by a Repository of the Ancients, allowing them to travel to worlds unknown to the Goa'uld. In "Rising", a list of Stargate addresses in the Pegasus galaxy is found in the Atlantis database. The SGC assigns designations to Stargate-accessible planets in the form P"xx-xxx" or M"xx-xxx". Samantha Carter explains in "The Broca Divide" that the designation "is based on a binary code the computer uses for extrapolation".