Apply the patch in D125 and see it in action.
Since COList only has 470 lines, we can quickly observe that all occurances are taken into account.
We can test the validity of the rng file by running the game. If it contains a wrong entry, it will complain when encountering the hidden property in a column.
The validity of the RELAX NG compact syntax file can be tested by executing `trang gui.rnc gui.rnc` and observing that the resulting `gui.rng` works as advertized.