quot; : 10, &quot;y&quot; : [0,1,0,0,0,0,0,0,0,1] }</code></pre>
<p>Matrix data and multi-dimensional arrays are indexed in row-major order.
For a Stan program which has data block:</p>
<pre><code>data {
  int d1;
  int d2;
  int d3;
  int ar[d1, d2, d3];
}</code></pre>
<p>the following JSON input would be valid:</p>
<pre><code>{ &quot;d1&quot; : 2,
  &quot;d2&quot; : 3,
  &quot;d3&quot; : 4,
  &quot;ar&quot; : [[[0,1,2,3], [4,5,6,7], [8,9,10,11]],
          [[12,13,14,15], [16,17,18,19], [20,21,22,23]]]
}<