With the AutoCAD Plant 3D Spec Editor, you can create and modify spec files using industry standard parts catalogs. You can also customize catalogs.
Use the Spec Editor to add parts to a spec. Set branch fitting preferences used in AutoCAD Plant 3D when routing pipe in the Branch Table Editor. Use the Catalog Editor to manage catalogs, modify the dimensional properties of piping components, and to create components.
Catalogs are used to create specs, and specs are used to route pipe in the 3D model, but they are not linked. Specs, catalogs, and the 3D model are independent after they are created. You can copy part information from a catalog to a spec. When the spec is complete the catalog is not required to use the spec. Likewise, a component added to the 3D model no longer requires the spec.