how do you specify field dependencies in an XML Schema?

Question

This is more of an generic XML Schema question, but if and how do you specify field dependencies in an XML Schema. For example, how would I say fieldB is required, if fieldA is provided ???

Answer 1

You could fake this using <choice> and/or <sequence>. For example, you could allow either nothing, fieldB, or fieldA and fieldB, but not just fieldA. This could lead to duplication, which you could prevent by defining a complexType.