About User-Defined Parameters in NC Sequences
You can define user-defined parameters for NC sequences. All sequences including existing and new sequences under a workcell can use these user-defined parameters. You can also enable the display of these parameters as PPRINT statement in the CL data.
The User-Defined Parameters dialog box lets you modify or update custom parameter values that you can associate with the NC sequences. The mfg_custom_sequence_param_file configuration option controls the access to this dialog box. The 
button for opening the User-Defined Parameters dialog box appears on the Parameters tab while defining an NC sequence only if you set the value of the mfg_custom_sequence_param_file configuration option to point to a valid user-defined parameter file. The user-defined parameter file must have a *.xml extension. If the XML file contains multiple definitions of workcell type or parameters, only the first definitions stated in the file are considered. While parsing the user-defined parameter file, if Creo NC encounters a parameter definition that is not valid, the entire file is ignored, and the user-defined parameters are discarded. Any changes that you want to make to the user-defined parameter definitions can be done only by editing the user-defined parameter file. To update these changes, you must reload the manufacturing model, confirm the new definitions, and then click > on the Manufacturing tab for the changes to take effect.
button for opening the User-Defined Parameters dialog box appears on the Parameters tab while defining an NC sequence only if you set the value of the mfg_custom_sequence_param_file configuration option to point to a valid user-defined parameter file. The user-defined parameter file must have a *.xml extension. If the XML file contains multiple definitions of workcell type or parameters, only the first definitions stated in the file are considered. While parsing the user-defined parameter file, if Creo NC encounters a parameter definition that is not valid, the entire file is ignored, and the user-defined parameters are discarded. Any changes that you want to make to the user-defined parameter definitions can be done only by editing the user-defined parameter file. To update these changes, you must reload the manufacturing model, confirm the new definitions, and then click > on the Manufacturing tab for the changes to take effect.The user-defined manufacturing parameters are stored within the manufacturing model. If you want to add or delete parameters or modify one or more existing parameters, you can do so only in the user-defined parameter XML configuration file. To delete all the user-defined parameter definitions from the manufacturing model, delete the mfg_custom_sequence_param_file configuration option and restart Creo Parametric. When you reopen the manufacturing model for which you deleted the custom parameter definitions, Creo Parametric prompts you to choose whether to delete the existing definitions or retain them.