Xilinx Answer #6724 : 1.5i SP2 - New SpartanXL speed files are available with updated -5 numbers.
Xilinx Answer #6252 : FPGA Configuration: Express Mode fails (INIT Low) for XCS40XL.
Xilinx Answer #6169 : Spartan - Spartan, Spartan XL, and Spartan-II bitstream compatibility