anchor.diff:  15|97|The Invasion of Time|150|https://en.wikipedia.org/wiki/The_Invasion_of_Time|The Sontarans invade Gallifrey.|
   16|98|The Ribos Operation|100|https://en.wikipedia.org/wiki/The_Ribos_Operation|To restore cosmic balance, the White Guardian requires the Key to Time.|
   16|99|The Pirate Planet|100|https://en.wikipedia.org/wiki/The_Pirate_Planet|The tracer leads to planet Calufrax in search of the second segment of the Key.|
  -16|100|The Stones of Blood|100|https://en.wikipedia.org/wiki/The_Stones_of_Blood|The tracer takes the Doctor, Romana and K9 to a stone circle on Boscombe Moor.|
  +16|100|The Stones of Blood|100|https://en.wikipedia.org/wiki/The_Stones_of_Blood|The tracer points to a stone circle on Boscombe Moor, where druids await the Doctor.|
   16|101|The Androids of Tara|100|https://en.wikipedia.org/wiki/The_Androids_of_Tara|In search of the fourth segment of the Key to Time, the TARDIS lands on Tara.|
   16|102|The Power of Kroll|100|https://en.wikipedia.org/wiki/The_Power_of_Kroll|In search of the fifth segment of the Key to Time, Romana is taken by Swampies.|
   16|103|The Armageddon Factor|150|https://en.wikipedia.org/wiki/The_Armageddon_Factor|In search of the final segment of the Key to Time, the TARDIS lands on Atrios.|
  
positive.code: 11|74|Planet of the Spiders|150|https://en.wikipedia.org/wiki/Planet_of_the_Spiders|Giant Spiders and Mike Yates feature in the Third Doctor's swansong.|
  12|75|Robot|100|https://en.wikipedia.org/wiki/Robot_%28Doctor_Who%29|After his regeneration, the Doctor investigates the robbery of top secret plans.|
  12|76|The Ark in Space|100|https://en.wikipedia.org/wiki/The_Ark_in_Space|The TARDIS materialises aboard the Ark, a space station in orbit around Earth.|
  12|77|The Sontaran Experiment|50|https://en.wikipedia.org/wiki/The_Sontaran_Experiment|The Doctor, Sarah and Harry arrive on Earth which is now a desolate wilderness.|
  12|78|Genesis of the Daleks|150|https://en.wikipedia.org/wiki/Genesis_of_the_Daleks|The Time Lords foresee Daleks conquering the Universe, and send the Doctor to stop them.|
  12|79|Revenge of the Cybermen|100|https://en.wikipedia.org/wiki/Revenge_of_the_Cybermen|The time ring returns the Doctor, Sarah and Harry to space station Nerva.|
  13|80|Terror of the Zygons|100|https://en.wikipedia.org/wiki/Terror_of_the_Zygons|Oil rigs off Scotland are being attacked by the Loch Ness monster.|
  
negative.code: 14|89|The Face of Evil|100|https://en.wikipedia.org/wiki/The_Face_of_Evil|The TARDIS lands in an alien jungle with a savage tribe: the Sevateem.|
  14|90|The Robots of Death|100|https://en.wikipedia.org/wiki/The_Robots_of_Death|The TARDIS lands on a huge sandminer as it travels across a barren landscape.|
  14|91|The Talons of Weng-Chiang|150|https://en.wikipedia.org/wiki/The_Talons_of_Weng-Chiang|The Doctor and Leela are attacked by stage performers in Victorian London.|
  15|92|Horror of Fang Rock|100|https://en.wikipedia.org/wiki/Horror_of_Fang_Rock|The team of the lonely Fang Rock lighthouse start disappearing in the fog.|
  15|93|The Invisible Enemy|100|https://en.wikipedia.org/wiki/The_Invisible_Enemy_%28Doctor_Who%29|Ill, the Doctor is injected into his own body to fight the infection.|
  15|94|Image of the Fendahl|100|https://en.wikipedia.org/wiki/Image_of_the_Fendahl|The TARDIS is drawn to Fetch Priory where Professor Fendelman experiments.|
  15|95|The Sun Makers|100|https://en.wikipedia.org/wiki/The_Sun_Makers|Arriving on Pluto, the Doctor is surprised to find it has breathable air.|
  