On Thu, Jul 23, 2015 at 7:52 PM, David Conrad <drc@xxxxxxxxxxxxxxx> wrote: > John, > > ... > > The root zone is NOT the entire top-level of the identifier space. It is the top-level of the subset of the identifier space that is comprised of (a) strings that are valid in the DNS protocol ... > > Even if you meant "what could potentially be placed in the root zone", this would still be limited by (a) by the simple fact that the root zone is a DNS protocol implementation artifact, not a namespace artifact, and is thus constrained by the limitations of the DNS protocol. If you truly mean the DNS protocol, as opposed to various user interfaces or conventions, labels in DNS names are binary byte strings restricted only by a maximum length of 63 bytes (and the minimum length zero is only permitted as indicating the root). Interesting byte values such as 0x00 or 0xFF work just fine inside labels in the DNS protocol. Thanks, Donald ============================= Donald E. Eastlake 3rd +1-508-333-2270 (cell) 155 Beaver Street, Milford, MA 01757 USA d3e3e3@xxxxxxxxx