phranque - 2:16 pm on May 26, 2011 (gmt 0)
HTTP/1.1 Status Code Definitions:
HTTP/1.1 Header Field Definitions:
although i would probably be most concerned with the Link: rel="canonical" header and the "X-Meta-" response headers (which aren't listed in the above reference and are typically defined in the document <head>), especially the meta robots header.
or the X-Robots-Tag header.
use the Live HTTP Headers plugin for FF or your favorite "status code/server header checker tool".