I never knew what it meant.....

Ok on occasion I do go to Wal-Mart to pick up a couple of things here and there. I always see this sign on the door "Code Adam" , and never knew what it meant.
Yesterday someone told me it's when a child is reported missing in the store, the announce "Code Adam" ( in reference to Adam Walsh, John Walsh, his father apparently worked with Wal-Mart to get this in place). At that point they "lock-down" the entire store. No one is allowed in or out until the child is found and/or the store is thoroughly searched.
Why aren't other stores doing this? Personally I think this is a great idea. Yes it may disrupt your shopping experience, but if it saves a child from being kidnapped and/or killed- isn't it worth it?
Shouldn't big box retailers and even shopping malls follow this example? I think it's way past time to help protect our kids.