Hello, I have reviewed current version of 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. [overview] This draft provides an extension to iCalender to support use of non-Gregorian recurrence rules. It first elaborates the difficulties to cope with the non-Gregorian calendar using the existing "CALSCALE" property in iCalendar. The "RRULE" property is thus extended to include an "RSCALE" element. The draft also explains how to handle the dates expressed by non-Gregorian calendar. [security consideration check] The security consideration section says that this draft does not introduce any additional security concerns beyond those described in RFC 5545, 5546, and 4791. I agree, since this draft simply added an "RSCALE" element; I do not think it may cause any extra security concerns. [status] I think this draft is ready for further process. Thank you. Take