An Attachment Point is a Z.Group node (or any node which inherits from Z.Group) that has been exposed for use within a parent symbol.
This allows points to be set up within a subsymbol that can be accessed from a parent symbol, something otherwise unaccessible, without having to go into or have a full understanding of the subsymbol.
Setting pivot points for rotation, locations for objects, and sections of a subsymbol in which to place objects are just a few of the examples where Attachment Points can be used.
Creating Attachment Points
A group node can be exposed as an Attachment Point by right-clicking on the node, selecting 'Expose as attachment point', and giving it a name. Nodes exposed as attachment points have a paperclip icon in the Hierarchy.
Clicking 'Expose as attachment point' again on an exposed node will remove its status as an Attachment Point.
Accessing Attachment Points
To access an Attachment Point from a parent symbol, an instance of a symbol with exposed Attachment Points will need to be instantiated and available within the Hierarchy.
Right-clicking on a subsymbol node within the Hierarchy and selecting 'New > AttachmentPoint' will give a list of available Attachment Points. Selecting one will create a child node under the subsymbol node relating to that Attachment Point.
If there are no Attachment Points within a given subsymbol then the 'New > AttachmentPoint' option will not be present.
Using Attachment Points
Dragging a node and placing it on the Attachment Point node within the Hierarchy will make it a child of the Attachment Point.
The example on the right shows an Attachment Point in the top left-hand corner of a subsymbol and a plane being dragged into the Attachment Point node within the Hierarchy.
The following article discusses the ways in which you can pass information between symbols.