What's the meaning of "xsd:extension base = …?

问题

What's the meaning of ? Does SubParameter type included all the information of MainParameter.type content? and attribute MyIndex attached.

  <xsd:complexType name="SubParameter.type">
    <xsd:complexContent>
      <xsd:extension base="MainParameter.type">
        <xsd:attribute name="MyIndex" type="xsd:nonNegativeInteger"/>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>

Thank you.

回答1:

You are declaring a type that extends MainParameter.type.

In other words, your new type "SubParameter.type" will have all the attributes and structure of MainParameter but with an additional MyIndex attribute.

来源：https://stackoverflow.com/questions/1939062/whats-the-meaning-of-xsdextension-base