I am working on a traditional country hutch that was featured in January/February 2007 of Fine Woodworking. I can't figure out how the top unit is secured to the lower case. The article and plans only describe cutting a groove along the back of the lower case and a rabbit along the bottom of the back of the upper shelf unit and then says "Cut the slots for the buttons that will secure the top to the lower case." Neither the slots nor the buttons nor their location are described in the article or plans. What does that mean, and where are you supposed to cut the slots? I always thought buttons mean covering a screw hole with a wooden plug, but I don't see any logical position for a screw and it hardly seems traditional. Does it have another meaning?