I am struggling to find the information I need from the Xilinx datasheet, perhaps someone could provide me with some pointers. I am working with a Virtex 4 FX100 in a FF1152 package. I have 20 MGTs to play with, arranged in 10 tiles numbered 101, 102, 103, 105, 106, 109,110, 112, 113 and 114. These are further arranged into columns. There must be a simple method for determining which tiles are in which columns, but I haven't worked it out. Perhaps a related problem is that I have no idea where the odd numbering scheme comes from. Any help would be greatly appreciated.