This class describes the parts and structure of a nodekit. Each class of nodekit has one SoNodekitCatalog (a static variable for the class). Internally, the catalog contains one entry for each "part" in the nodekit's structure. Users can query the catalog for information about each entry in the catalog. This information can be obtained either by part name (an SbName unique for the part within the catalog) or by part number (an index into an array of parts).

Note that, although the catalog for a nodekit class may contain many entries, each instance of that class is not initially created with all of these parts intact. Rather, each instance of the class has its own parts list which keeps track of which parts the user has created. The nodekit uses the catalog as a guide in creating new nodes as its descendants; the standard addChild(), removeChild() and other SoGroup methods are protected, so that users must create descendants indirectly by asking the nodekit to get and/or set the different "parts" in the catalog.

The first entry in any SoNodekitCatalog corresponds to the nodekit itself. Its partName is "this" and its partNumber is 0. All other parts in the catalog are described relative to "this."