If the value of the $LCA environment variable is incorrectly set OR the $LCA variable is not referenced in the mgc_location_map file, ENWrite (Mentor's EDIF netlist writer) will be unable to traverse the hierarchy of XIlinx macros, and will instead describe them as "black boxes" (i.e., primitives) rather than write out their full schematic descriptions.
ソリューション
This is easily fixed by setting $LCA to the pathname of the Mentor-interface software (DS344).