/a></span> <span class="operator">|</span> <span class="keyword">undefined</span></code></pre><div class="table"><table><tr><th></th><th>Type</th><th>Description</th></tr><tr><th><code>id<span class="operator">?</span></code></th><td><code><span class="builtin">string</span></code></td><td><p>An optional <a href="/api/common/type-aliases/identity/id/"><code>Id</code></a> for accessing a <a href="/api/metrics/interfaces/metrics/metrics/"><code>Metrics</code></a> object that was named with an <a href="/api/co