I have reviewed this document as part of the Ops area directorate's ongoing effort to review all IETF documents being processed by the IESG. These comments were written primarily for the benefit of the Ops area directors. Document editors and WG chairs should treat these comments just like any other last call comments. This document describes the structure of the control messages that were historically used with the Network Time Protocol. Being historical document, I would expect the document to give a description on what the Control Message are for, who is the sender, and who is the receiver, is the Control Message broadcast to every node in the network? or only between some nodes? The document describes the bits in detail for Mode =6 and Mode =7. The RFC1305 has a lot of information, but can't pinpoint the Control message's purpose. Are the control messages for distributing time from Stratum 0 to Stratum 1? or between network nodes? Thank you. Linda Dunbar