span class="op">=</span> <span class="cn">NULL</span>,</span>
<span>  X <span class="op">=</span> <span class="cn">NULL</span>,</span>
<span>  W <span class="op">=</span> <span class="cn">NULL</span>,</span>
<span>  stat <span class="op">=</span> <span class="cn">NULL</span>,</span>
<span>  covs <span class="op">=</span> <span class="cn">NULL</span>,</span>
<span>  trait <span class="op">=</span> <span class="cn">NULL</span>,</span>
<span>  fit <span class="op">=</span> <span class="cn">NULL</span>,</span>
