; these terms will appear as additional components in both the fixed and the random-effects terms. This functionality is <em>experimental</em> for now. We recommend using <code>REML=TRUE</code>. See <code><a href="https://rdrr.io/pkg/mgcv/man/s.html" class="external-link">s</a></code> for details of specifying smooths (and <code><a href="https://rdrr.io/pkg/mgcv/man/smooth2random.html" class="external-link">smooth2random</a></code> and the appendix of Wood (2004) for technical details).</p></li>
</ul></div>