[LAU] asoundrc questions

I'm trying to follow the example .asoundrc provided at http://alsa.opensrc.org/RME_Hammerfall_.asoundrc I've read elsewhere that references to 'card 0', 'card 1' etc. can not be relied upon to always refer to the same card. It wouldn't matter, I suppose, if there are only two identical cards, but I have another two. One is switched off in the BIOS, but the other always shows up like: card 0: NVidia [HDA NVidia], device 3: HDMI 0 [HDMI 0] But not always as 'card 0'. I've configured a udev rule which always names my two RME cards as RME_1 and RME_2, so can I use those names in place of the card N designations? Are the strings which contain "9652" in the example just made up? Or are they references to the author's udev dabblings? The first one is particularly confusing as it's the only case of rme9652_s. Lastly; I don't suppose there's anything which can sanity test an .asoundrc, so will there be complaints logged somewhere if I get it wrong? -- Thanks again, John.