1.01.383 Unit_ResourceQuantityRequirements

<Unit_ResourceQuantityRequirements>
<Update>
<Set ResourceType="RESOURCE_IRON"/>
<Where UnitType="UNIT_IRONCLAD"/>
</Update>
</Unit_ResourceQuantityRequirements>

This functions as intended but has a weird side effect of removing coal, the original resource required to build ironclads from the top UI.

Ironclads and Factories can be built to limit everything functions behind the scenes except for the UI

You can add additional requirements but using the delete command also causes the UI problems.

For reasons I don't entirely get, it seems that strategic resources sometimes don't appear in the topbar unless there's a unit that requires them. ISTR there's something can be done to make them appear otherwise, and it's possible that the vanilla data doesn't do that.