Nothing. The scenario designer has just designed them as a box and not filled in every action square in the middle. Just ensure your forces touch and sit on the highlighted border to claim. They got popular there for a while as a way to minimise the chance that the one odd infantry pixeltruppen you miss doesn't mean you don't don't claim the objective.
there any available for download I am always up for a new scenario?? The map of his i saw for the upcoming d-day mod look great...i am always up for a good scenario.... i check the depot over on the BF forums at least a couple times a week.... CMBS CMBN CMCW CMSF
Some of my work is also in the "Rome to Victory" and "Fire and Rubble" modules for CMFI and CMRT respectively. The CMFI scenarios are fictional but the CMRT campaign and scenarios are based on historical events. Well except the partisan one which pretty 'Hollywood'.