 planning problems involve making decisions on planning
units. These decisions are then associated with actions (e.g., turning a
planning unit into a protected area). Only a
single decision should be added to a <code><a href="problem.html">problem()</a></code> object.
Note that if multiple decisions are added to an object, then the
last one to be added will be used.</p>
    </div>
    <div class="section level2">
    <h2 id="see-also">See also<a class="anchor" aria-label="anchor" href="#see-also"></a></h2>
