The schema should not require a particular sequence of element tags. This is unusual in my experience for schema, and I believe it unnecessarily increases the complexity of creating valid PBCore XML. I also don't see any upside to people who are writing PBCore parsers to have the tags in a particular order. I believe most parsers simply read the XML and create a data object which may no longer preserve the order.
The schema should not require a particular sequence of element tags. This is unusual in my experience for schema, and I believe it unnecessarily increases the complexity of creating valid PBCore XML. I also don't see any upside to people who are writing PBCore parsers to have the tags in a particular order. I believe most parsers simply read the XML and create a data object which may no longer preserve the order.