During session establishment, a VTAM® session initiation record called a CINIT is created and sent to the primary application. Attached to the CINIT is a control vector 64 (CV64) that is created by Telnet to provide additional information about the Telnet connection. The CV64 control vector contains four sub-vectors. The CV64 control vector and the four sub-vectors are all defined as key/length vectors.
X'64mm', where mm is (ii + 2) + 4 + (hh +2 (if SBV85 present)) + 19 (if SBV86 present)
X'81ii', where ii is 06 for IPv4, 18 for IPv6
X'8202'
X'85hh', where hh is 1 + DNS name length
X'8611'