Special Operations Officer

Special Operations Officer, or Spec Ops Officer for short, is a Covenant Sangheili (Elite) rank.

Rank
Spec Ops Officer is rather a position/office than a actual rank per se (Much like how Battalion Commander is a position but Major or Lieutenant Colonel is the actual rank).

Summary
The role of such Elites is to lead a troupe of lower ranked Special Operations forces, much like the role of the higher ranked Special Operations Commander, but the troupe that Spec Ops Officers command holds fewer troops than the one commanded by Special Operations Commanders.

Armor
In Halo 1, it's impossible to see any armor difference from other Special Operations Elites, but in Halo 2, they are the only Elites that have black-colored armor.

Halo: The Flood
In the novel Halo: The Flood, a Special Operations Officer named Zuka Zamamee joined other Covenant forces in boarding The Pillar of Autumn, but were shot in the head by the Master Chief, and were extremly wounded. From that moment he wanted to get the permission to kill Master Chief. When he had the permission, he started to lay several traps for S-117, but he survived the traps, and Zamamee was finally killed by John-117 on The Pillar of Autumn when he tried to ambush him from a elevator.