Sirius, James, Remus, and Peter: The map's creators " The magic used in the map's creation is advanced and impressive it includes the Homonculous Charm, enabling the possessor of the map to track the movements of every person in the castle, and it was also enchanted to forever repel (as insultingly as possible) the curiosity of their nemesis, Severus Snape." - Description of the magic involved in the map's creation The Chamber of Secrets never appeared on the map either because the creators never knew of it or it was unplottable as well, since when Ron and Hermione were in it collecting basilisk fangs, they did not appear on the map similar to the Room of Requirement. Also, it did not seem to show unplottable rooms, as it was Dobby and not the map that revealed the existence and location of the Room of Requirement. One of the map's possible flaws was that it did not differentiate people who had matching names (the shared names were not given a Junior or Senior at the end). It was also capable of accurately identifying each person, and was not fooled by animagi, Polyjuice Potions, or invisibility cloaks even the Hogwarts ghosts were not exempt. Not only did it show every classroom, every hallway, and every corner of the castle, but it also showed every inch of the grounds, as well as all the secret passages that were hidden within its walls and the location of every person in the grounds, portrayed by a dot. The Marauder's Map was a magical document that revealed all of Hogwarts School of Witchcraft and Wizardry. THE MARAUDER'S MAP" - The Marauder's Map Purveyors of Aids to Magical Mischief-Makers " Messrs Moony, Wormtail, Padfoot, and Prongs