will say <code>supply</code>
</p>
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<h4 id="org153ff37"><span class="section-number-4">2.5.3.</span> Constraint</h4>
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<p>
The <code>constraint</code> field will always show one of three values: <code>forbidden</code>, <code>optional</code> and <code>required</code>. These are colour-coded to match the display on the map, when the map is set to show constraints. See <a href="#concept-constraints"