2002 2005-09-07 19:47:49 +0000 R-024: Derivation by Restriction: pointless occurrences 2009-04-21 19:24:49 +0000 1 1 1 Unclassified XML Schema Structures: XSD Part 1 1.0 only All All CLOSED LATER P2 normal --- 1 sandygao ht www-xml-schema-comments oldest_to_newest 5794 0 sandygao 2005-09-07 19:47:49 +0000 The constraints for "Particle Valid (Restriction)" indicate that pointless occurrences of sequence, all and choice should be ignored. By doing so, it is possible that certain derived types which would otherwise be valid restrictions of their base types, become invalid. See the following for more information, and an example: http://lists.w3.org/Archives/Public/www-xml-schema- comments/2001AprJun/0230.html Note that Achille Fokoue posted another example illustrating this problem. See the following for more information: http://lists.w3.org/Archives/Public/www-xml-schema- comments/2001JulSep/0111.html Note also that a subsequent email on pointlessness was sent in by Gareth Sylvester-Bradley: http://lists.w3.org/Archives/Public/www-xml-schema-comments/2003JulSep/0040.html 5795 1 sandygao 2005-09-07 19:48:33 +0000 The WG has discussed various solutions: - Leave the rules asis. - Modify the rules for pointlessness to indicate that they "may" apply instead of "must" apply - define a new algorithm Resolution The WG has decided that although the rules have some awkward results, they are not in error. It will be put on the list of issues to consider for a future revision of XML Schema.