Note that there are two versions, the Netscape one and the Microsoft one. The Netscape one used renegotiation, the Microsoft one just sends a new ClientHello af

Note that there are two versions, the Netscape one and the Microsoft one. The Netscape one used renegotiation, the Microsoft one just sends a new ClientHello after the Certificate message. I think SChannel supported both of them and looked at the certificate to determine which one to use, while NSS supported only the Netscape one.