The catalogs provided with AutoCAD Civil 3D are read-only by default. When you create a new catalog, it is writable (read-write) by default. To set a catalog’s access right status, the <AccessRight> tag in the catalog .atc file should be set to 1 for read-only, and 0 for read-write. For more information on .atc files, see Assemblies and Subassemblies in the AutoCAD Civil 3D Help.