Is anyone able to provide a definitive guide to the labelled icons in Xcode 4’s debug area variable list? Here’s a list of what I have at the moment. I can’t figure out what they mean:

It’s not intuitive. For example, I have BOOL and NSMutableString objects, both with green ‘i’ icons. I haven’t been able to find a list of what these icons mean, either in Xcode’s documentation, or online. Thank-you,
Steve.
They appear to be:
Here are some links which discuss that part of the interface:
edit: updated with Steve HHH’s suggestion
edit2: updated following information from a WWDC 2012 presentation, “Debugging in Xcode” (video no longer available)