Mounting is the dynamic grafting of another tree at a given node in the hierarchy so that it becomes a subtree of the hosting tree. Conversely, unmounting (pruning) of a subtree is also supported.

 <node id="mymountpoint">
    <img src="minus.gif"/>
    <mountpoint weight="1.0" delaymount="true">
        <a href="mount.xml"/>

The embedded <a> tag indicates the URL to retrieve the XML description of the tree to be mounted.

Depending on the value on the delaymount attribute, the mounting of target tree will be delayed until a mouse double-click happens (this is the default behaviour) or will proceed immediately upon parsing.

The weight attribute is used to reserve hyperbolic space during layout. It can be either an estimation or precise computation. Pressing Alt key while hovering over a node will yield the weight of existing nodes. The weight is recursively computed as :
1+log(sum of children's weight) with a childless node 's weight being 1