Hi all, please pardon me if i post to wrong section (it took me 3 days to even gain access this site).
In your xsd tutorial, the Example 2 description is plain wrong, and it is confusing people. The faulty page is here: https://www.w3schools.com/xml/el_all.asp The error must be there for a long time, it even has its own post on stackoverflow https://stackoverflow.com/questions/5677154/how-do-i-make-items-optional-in-xsall
Quote: "The example above indicates that the "firstname" and the "lastname" elements can appear in any order and each element CAN appear zero or one time!"
To allow each subelement to be missing, the minOccurs attribute must be put to the subelements, not the xs:all itself.
Please fix the embarassing error. :-)