-doc"><p><code>block</code> type keeps a reference to a block of memory and to the nodes sharing that block.</p></div></div><div class="odoc-spec"><div class="spec type anchored" id="type-attr"><a href="#type-attr" class="anchor"></a><code><span><span class="keyword">and</span> attr</span><span> = </span><span>{</span></code><ol><li id="type-attr.op" class="def record field anchored"><a href="#type-attr.op" class="anchor"></a><code><span><span class="keyword">mutable</span> op : <a href="#type-op">op</a>;</