I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG. These comments were written primarily for the benefit of the security area directors. Document editors and WG chairs should treat these comments just like any other last call comments. The document sets out architectural considerations for location and location privacy systems. As such it is essentially an extended set of security considerations. The document is very thorough and describes both the problem and generalized approaches addressing requirements that arise. In my opinion it is suitable for publication in its current form. I have no particular issues with the document except to note the following: 1) Legal risks of collecting location information. You can't lose what you don't have. Sites that collect and store credit card numbers expose themselves to the risk of penalties should they be compromised. Sites that collect location information they don't need may be opening themselves to unnecessary liability. Implementing privacy architectures is thus not merely a matter of compliance, it is potentially a means of mitigating liability risk. 2) Unintended location information GPS and similar devices are designed to collect location information, but many Internet technologies leak information that has a high correlation with position. Even an IP address can be tracked down to a street level address in many instances. The issues raised in this document are thus of wider application than technologies intended to provide location information. -- Website: http://hallambaker.com/