Editing The Core

The Core is the most indispensable part of a Halo. It directs and controls every other aspect of the ringworld, and is the location that the rings may be activated by way of the [[Activation Index]]. [[Containment protocol]] dictates that the Index must be physically brought into contact with the Core by a [[Reclaimer]]. According to [[343 Guilty Spark]], he was not allowed to perform this action (although not that he ''couldn't''){{Ref/Novel|TF|Page=255|Quote=Protocol does not allow units of my classification to perform a task as important as the reunification of the Index with the Core.}} and [[Jiralhanae]] [[Brute Chieftain|Chieftain]] [[Tartarus]] was seemingly unable to do so. Once the Index has been 'reunified' with the Core, the Installation's firing sequence begins. However, if the Index is forcefully removed before the fire sequence begins, all [[seven]] Halo rings go into standby mode, ready to be fired remotely from [[Installation 00|the Ark]].

The Core seems to be restricted-access according to 343 Guilty Spark's protocol, and access by unauthorized [[AI]] constructs is strictly forbidden.{{Ref/Novel|TF|Page=256|Quote=A construct? In the core? That is absolutely unacceptable!}} An AI inside the Core has a surprising amount of control: [[Cortana]] was able to make 343 Guilty Spark fall to the floor just by waving her hand, indicating the ability to override some of the [[Monitor]]'s powers.

During the [[Mission to Installation 03]], [[monitor]] [[859 Static Carillon]] teleported the [[Ur-Didact]] to the [[Control Room (Installation 03)|Installation's control room]] in order to aid [[Blue Team]]. Determined to kill the [[Promethean]] warrior, Master Chief [[John-117]] went to confront the Didact and inserted the ring's Activation Index with the installation's Core. John manually disabled Gamma Halo's safety protocols, allowing the monitor to scuttle the Halo segment containing them into the [[Composer's Forge|planet installation]] below.{{Ref/Comic|HE|Issue=10}}

[[Installation 04]]'s Core was, at one point, inhabited by Cortana. While inside, she obtained a tremendous quantity of knowledge. Within an instant, this position enabled her to learn of the [[Flood]] and [[Captain (Navy)|Captain]] [[Jacob Keyes]]'s plight against them. More importantly, it enabled her to stop the installation from firing and steal the Index when [[John-117]] had attempted to activate Halo's firing process.{{Ref/Level|CE|Two Betrayals}}

During the [[Battle of Installation 05]], [[Tartarus]] forced the captive [[Miranda Keyes]] to connect [[Installation 05]]'s Activation Index with the installation's Core. As the Halo's firing process was initiated, the Index was moved to the beam in the center of the control room. Before the ring could fire, however, Keyes removed the Index from the beam, aborting Installation 05's firing sequence.{{Ref/Level|H2|The Great Journey}}