Well that is good news.  thank-you Zeilap.

I notice that the list on that page does not include many/most of the recent altcoins.  This makes me wonder if those altcoin devs are aware of the address prefix, and (in general) are modifying them, or not.

Also, in some limited testing with litecoin testnet addresses, I see that they are prefixed with m, the same as bitcoin testnet.  So that means that any address identification routine based on the 1st byte would be unable to distinguish between BTC and LTC, unless I am missing something.

Just observations.  Thanks again for the pointer.