Yup, AFAIK that's the sat nav system for Japanese market E39s only - apparently it's totally incompatible with European BMWs as it uses different connectors / functionality / protocols etc and will not play European map DVDs. In short it's useless for European E39s. RealOEM lists it for E39s but mentions it's for the Japanese market.

I actually saw this sat nav (or one exactly like it) on eBay recently and I e-mailed the seller to tell him it wouldn't work with European E39s as he'd got it listed as compatible with all E39s as well as other BMWs. He then changed his listing to basically say "check for yourself regarding compatability" and that he wouldn't accept refunds or responsibility, but made no mention of the info I'd given him about it not working in Europe and it being for for the Japanese market only. A somewhat misleading and unfair sale I thought...