Ed, Forgive me, but you didn't answer my question. How do I tell my credit card company's billing system which harris.com to use? What keeps my data entry from becoming ambiguous over time? Eliot Ed Gerck wrote: >>How does my credit card company's billing system know which harris.com >>to transmit my bill to? What unique attributes does it use to choose >>between the two domains? > > > Eliot, > > that's easy. Your credit card company has a previous relationship with > you and knows which harris.com to transmit to. Possibly, to the harris.com > defined at your root. In pretty much the same way, btw, that the credit card > company can disambiguate between you and any other Eliot Lear.