From Halopedia, the Halo wiki
Covenant marksman rifles utilize smart-linking technology, with both the focus rifle and the particle beam rifle using the same smart-link firmware with varying scope magnifications. The smart-link feed used by both of the weapons displays the rifle's remaining power, accumulated heat level, and diagnostic information. The smart-link feed allows semi-automatic adjustment of the plasma beam angle when interlinked with the hardware in Sangheili combat harnesses or Kig-Yar marksman sets, allowing the rifle's operator to track targets without adjust their aimpoint at distant targets.
Smart-linking acts as the fictional basis for the new "smart scope" Spartan ability in Halo 5: Guardians. The smart scope allows players to activate a holographic zoom-in overlay with an enhanced targeting reticle while using any ranged weapon. Apart from easing the player's aiming the weapon's accuracy is not affected by the smart scope.
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