The types of the array or slice index (always <code>int</code>)
and element, or of the map key and value respectively,
must be <a href="#Assignment_compatibility">assignment compatible</a> with
-the type of the iteration variables.
+the type of the iteration variables. The expression on the right hand
+side is evaluated once before beginning the loop. At each iteration
+of the loop, the values produced by the range clause are assigned to
+the left hand side as in an <a href="#Assignments">assignment
+statement</a>. Function calls on the left hand side will be evaluated
+exactly once per iteration.
</p>
<p>
For strings, the "range" clause iterates over the Unicode code points