SDL Tridion Schemas can be divided in two categories, a Tridion Web Schema and a W3C Schema.
The first variant (also known as a Simple Schema) does not allow attributes and only accepts certain data types. The second variant (also known as Complex Schema) will allow you anything supported by http://www.w3.org/2001/XMLSchema. But W3C Schemas don't have a design tab (you have to edit the Schema directly in the source tab or use an external editor via WebDAV), and Components based on such a Schema, don't have a form based UI (you have to edit the XML directly in the source tab of the Component or use an external editor via WebDAV).
That all being said, if you need to have this XML and you have a way of editing it, a W3C Schema is definitely the way to go, since it will ensure your XML is validated on save of the Component.
As an alternative, you could consider creating an
id element and use XSLT to transform your Tridion XML into the required XML (at render/publishing time in a TBB for example), while still continue to use Tridion Web Schemas. But this won't work if you want to update the XML of the Component with the outputted XML of course.