The URN resolution code is built into Magento directly.
Luckily, it’s pretty easy to associate URNs with real files in your local site.
Put the cursor in the URN then click on the red light bulb to the left that will appear and select “Manually Setup External Resource” from the list.


This note is a quick note describing how to do these steps.
(Official documentation is coming really soon.) Some examples of XSD URIs that have changed: The new URNs no longer care about the path relative to the other module (which gets messed up when you have some modules under ‘vendor’ and some locally developed modules still under ‘app/code’).
For example, a field that the European Payment Council does not regard as compulsory, may still be compulsory at a national level.
Similarly, a field with six available options, may only have four options at a national level.
This is what you will see after loading up the new code.