When attempting to specify an ordering for an index being created in the XMLDB editor, it strips the space between 'examplefield DESC' and makes it 'examplefielddesc' and will not allow creation stating the field doesn't exist. If you manually change the install XML to have the field 'examplefield DESC', the index is properly created, and if you use an upgrade.php script and manually change the field to 'examplefield DESC', the index is properly created.