Occurrence Types

Depending on the components it carries, an occurrence is designated by a different name in Pixyz Studio's user interface, API and Documentation:

Occurrence type	Description	Common Name
Part occurrence	An occurrence with a `Part component` is a `Part occurrence`, more commonly called `Part`. For example, the function `Merge Parts` merges together several Part occurrences in one resulting Part occurrence, and combines their geometries in its `Part component`.	Part
Assembly occurrence	An occurrence with no `Part component`, and having other occurrences as children, is called an `Assembly occurrence`, or `Assembly`. An Assembly is basically a node used to store other nodes, like a group or a folder. For example, the function Merge Parts By Assemblies finds all the Assembly occurrences in the Tree and merges their Part occurrences children as one resulting Part occurrence.	Assembly
Empty occurrence	An occurrence containing no geometry (no `Part component` or a `Part component` containing no geometry), no light (no `Light component`) and having no children, is called an empty occurrence. For example, the function Delete Empty Occurrences finds all the Empty occurrences in the Tree and deletes them.	Empty occurrence
Light Occurrence	An occurrence with a `Light component` is a `light occurrence`, or `light`.	Light

In the Product Structure, each occurrence type displays a different icon before its name:

About Icon's color

Depending on its status, an occurrence' icon will be displayed in the Product Structure with a dedicated color:

A cyan icon corresponds to an occurrence owning a prototype, and not expanded in the tree.
An orange icon corresponds to an occurrence having children, and expanded in the tree.
A gray icon corresponds to an occurrence not owning a prototype, and not expanded in the tree.