I never heard of having to rename a file before flashing. I mean it's no different than a Word file, in the sense that renaming it won't change the content inside. As long as you push the right file. When you download a new BIOS version there will be only one .cap file anyways so you cannot make any mistake. Bottom line, I don't think the file name is important, you could name it "totalcrap.cap" as long as it contains the right version for your BIOS it will work.
Or I think I understand now, you might have been reading the wrong part where they instruct you how to automate the flash, like if it's done from a script or something, the script might look for a specific file name, but if it doesn't find it, then nothing will happen you'll probably just get an error that file was not found and no harm will be done.