XML

If you want to generate XSD from XML, then you can use Free XML to XSD generator | Online Tools to see how this works, just paste in the following XML:

<parent>
  <first>AAA</first>
  <second>999.99</second>
  <third>XXX</third>
  <aaa>9</aaa>
  <aab>99</aab>
  <aac>999</aac>
  <aad>9999</aad>
  <aae>99999</aae>
  <bbb></bbb>
</parent>
For more help on understanding XSD data types then check Datatype Reference.