XSD: How to validate the XML file according to value of some tag?

Question

I was trying to validate this XML file ... where if

1. is \"Y\" then must appear

2. if

Answer 1

It's a known fact that this is a handycap of XML schema. But I would appreciate your approach of trying the tag. It could be successful if your conditions were something like this:

1. If is required and appears first then isn't required (and appears as second tag)
2. If is required and appears first then isn't required (and appears as second)

The code is: