5 May 2008 Makoto Murata and Hisashi Miyashita Abstract The RELAX NG schema in RFC 4287 (The Atom Syndication Format) does not provide full validation of Atom feeds containing extensions. Rather, this schema skips extension elements and attributes, even when extension elements further contain Atom feeds or entries. This document shows that ISO/IEC 19757-4 Namespace-based Validation Dispatching Lan