Eight-symbol addresses are introduced in "The Fifth Race", opening up new plot lines by connecting Stargates to different galaxies. The additional symbol acts as a type of "area code". Such connections, in comparison to seven symbol codes, require substantially more energy to complete a functional wormhole – much more than any standard dialing method can provide. In the first instance, opening an intergalactic wormhole is shown to exceed the total power generation capacity of the SGC at the time. O'Neill fashioned an additional power source using spare parts and the liquid naquadah power core of a staff weapon using the same enhanced knowledge that had allowed him to determine this address in the first place, but this new power source only functioned twice and required repair work to operate the second time. A fully charged Zero Point Module (ZPM) can provide enough power for regular travel between galaxies. The 8th chevron is a key element in the Stargate Atlantis series, allowing travel to the Pegasus Galaxy. With the stargates of the Milky Way, with 38 address symbols and one point of origin, there are 63,606,090,240 possible seven symbol co-ordinates. With the stargates of the Pegasus or Destiny, with 35 address symbols and one point of origin, there are only 33,891,580,800 possible seven symbol co-ordinates.