From Silver Sun Republic Codex

TACON or Tactical Control is the lowest level of command authority in the Republic's Military Structure. TACON is sometimes referred to as "Siege Calling" or "Raid Calling" as a whole and is where the individual direction of forces lives. For the Republic this typically resides as the Company level, however, subordinate command can happen within Lines and Lances when TACON is broken down further. TACON is thought of as the "trigger pulling" where forces maneuver on the individual level in combat. The standard opening to a fight is to engage as a whole Company and communicate internally as targets, threats, and vulnerabilities are observed. In the event that Lines or Lances are broken out, then TACON resides with the leader at that echelon. The Company Commander may still issue orders to the whole group in a direct manner, so that authority and control still exists even though smaller teams may be operating independently.

By understanding TACON vs OPCON, a Commander and their staff can ascertain the appropriate level of detail involved in planning and execution. Both of these concepts are critical elements of Command and Control.