Final answer:
MAJCOMs provide the commander-in-chief with a list of their Command's Command Post designations showing merged units and their titles.
Step-by-step explanation:
MAJCOMs (Major Commands) are responsible for overseeing the various units within the U.S. armed forces, such as the Army, Navy, Marine Corps, and Air Force.
They provide a list of their Command's Command Post designations to the commander-in-chief, who is the civilian leader of the military.
This list depicts which units have been merged and their titles.