The preceding sections have described the main HHED commands used for building continuous density systems with tied parameters. A further group of commands (JO, TI and HK) are used to build tied-mixture systems and these are described in Chapter 10. Those remaining cover a miscellany of functions. They are documented in the reference entry for HHED and include commands to add and remove state transitions (AT , RT ); synthesise triphones from biphones (MT ); change the parameter kind of a HMM (SK ); modify stream dimensions (SS , SU , SW ); and expand HMM sets by duplication, for example, as needed in making gender dependent models (DP ).