http://lists.w3.org/Archives/Public/public-webappsec/2012Oct/0004.html
This bug report on CORS, that the "Last-Event-ID" header should be a simple header, (along with Origin and Referer based on the status of actual implementations) is the last substantive change to the document that remains unresolved. I would like to propose we add "Last-Event-ID", "Origin" and "Referer" to the set of simple headers. Are there any objections, concerns or comments? Thank you, -Brad Hill
