Author XSD to allow extensible element

[Malance]

I want to author an XSD to validate against XML files. An example of the XML file may look like this:\[code\]<person> <fullname>John Doe</fullname> <age>25</age> <gender>male</gender></person>\[/code\]One of the requirement is that the \[code\]<person>\[/code\] tag is extensible, meaning that besides the 3 required child elements above, it can contain arbitrary elements with any names. So this document would be valid when validated by the XSD.\[code\] <person> <fullname>John Doe</fullname> <age>25</age> <gender>male</gender> <address>USA</address> <profession>worker</profession></person>\[/code\]I read about the \[code\]<xs:any />\[/code\] element, but XSD doesn't allow me to put \[code\]<xs:any />\[/code\] inside a \[code\]<xs:all />\[/code\] element. I want the \[code\]<fullname>\[/code\], \[code\]<gender>\[/code\] and \[code\]<age>\[/code\] elements to be required, and each of them must appear exactly one. Other than that, there can be zero or many optional elements. Is it possible to achieve this with the supported XSD rules?