Xilinx Tutorial
As you can see above, the Macro "H2" has 6 inputs and 2 outputs. This is a result of a schematic that contains gates, wires, etc that were combined to make this Macro. If you look up at the right, the "SC Symbols" contain macros that I had created prior, like the ALU, 8BITANDADD, as well as the XC4000E supplied macros. All of my macros are collectively kept in the 141Lab2 library, as shown.