Validating XForms Syntax with oXygen and NVDL

Adding this line:

<?oxygen NVDLSchema="file:/C:/Program%20Files/Oxygen%20XML%20Editor%209/samples/nvdl/xhtml-xforms.nvdl"?>

To the top of your Xforms will cause the form to be validated using the standard oXygen NVDL schema - this aids the process of authoring valid XForms code by offering XForms-aware syntax highlighting and error checking. I have found this to be really useful, so I hope it helps others.

Note:
file:/C:/Program%20Files/Oxygen%20XML%20Editor%209/

This is the path for a default install of oXygen 9.1 for windows (C:\Program Files\Oxygen XML Editor 9\)