Excellent response. Your spot on.

Just a quick add on though. Center MIA charts are not the real MIA. An MIA is 1000 AGL in non-mountainous areas and 2000 AGL in mountainous areas within 4 miles laterally. Center MIA charts are a very rough safe estimate of the real MIA. For example, you may have a few high mountains in a certain area that derives the MIA box on the center chart that sits above the sector. In reality if a pilot really wanted to use his sectional he could be below the center derived MIA and be 100% legal. This is because there would be an insane amount of MIA boxes and become pretty cumbersome when you pull up your MIA map on your radar.