*.sv file VERIFY section differ if previous section is PROGRAM or CHECKING SILICON ID

[Altera_Forum]

Hello, 

 The context is a embedded system running Linux and using urjtag ( http://urjtag.org/ ) software to verify and eventually program a 5M240ZM68 device.using a *.svf file. The idea is to test the CPLD integrity by using a VERIFY operation and if any error is found, then the CPLD is programmed with a PROGRAM operation (and tested again). To do that, we actually have to generate two *.svf files: a first one that contain the VERIFY section and a second one that contain a PROGRAM section, making the whole system useless if for some reason the two files are not coherent. Since the PROGRAM *.svf file always contain a VERIFY section, I tested how I can just skip the BULK ERASE and PROGRAM sections to generate on the fly a VERIFY *.svf file. This almost work as I observed only a single bit different from the vanilla VERIFY *.svf file in the very first line that check the TDO output:  On the PROGRAM *.svf file, the VERIFY section is:  SIR 10 TDI (203); RUNTEST 4 TCK; SDR 13 TDI (0000); SIR 10 TDI (205); RUNTEST 4 TCK; SDR 16 TDI (FFFF) TDO (7FFF) MASK (FFFF); SDR 16 TDI (FFFF) TDO (FFFF); SDR 16 TDI (FFFF) TDO (BFFC); SDR 16 TDI (FFFF) TDO (F9E7);  On the VERIFY *.svf file, the VERIFY section is:  SIR 10 TDI (203); RUNTEST 4 TCK; SDR 13 TDI (0000); SIR 10 TDI (205); RUNTEST 4 TCK; SDR 16 TDI (FFFF) TDO (7BFF) MASK (FFFF); SDR 16 TDI (FFFF) TDO (FFFF); SDR 16 TDI (FFFF) TDO (BFFC); SDR 16 TDI (FFFF) TDO (F9E7);    The only difference is this line:  SDR 16 TDI (FFFF) TDO (7FFF) MASK (FFFF); SDR 16 TDI (FFFF) TDO (7BFF) MASK (FFFF);  A 'B' (1011) instead of a 'F' (1111), a single bit is wrong, making the urjtag SVF player emmit an error message like if the VERIFY have failed.  My question is to understand this difference. Is there some bits that are not important for the VERIFY check ? If yes witch one and why the MASK is not set appropriately ? If not how can I calculate the correct TDO value to be expected ? I am afraid that without a full understanding of the difference, I could not have a reliable system that don't break in a update years after it hit the market.  Best Regards,