Those are probably the extension packs. Extension packs consist of two parts, an e-book that provides the documentation and a set of built in functions (in a DLL) that extend Mathcad's functionality. Currently the extension packs are actuallyh packaged in the base Mathcad, but the DLL's are not available unless you buy the license for them. The e-books, however, are just Mathcad worksheets and are installed and available whether or not you buy the extension packs. But the DLL based functions used in these e-books will not work unless you buy the extension packs.
