Which should come first: code, XML Schema, or binary specification?

Hi Folks,

I am examining Microsoft Visio.

It is a nice drawing application. You can create neat pictures.

You can save your drawing as a binary file.

You can also save your drawing as an XML file which conforms to an XML Schema for Visio.

So there are three components:

1. Code which expresses the capabilities of the application

2. XML Schema which expresses the capabilities of the application

3. Binary specification which expresses the capabilities of the application

In the development of an application which should come first: code, XML Schema, or binary specification?

/Roger