Model-Based Definition > Model-Based Definition > Working with Model Properties > Materials > About Material Parameters
  
About Material Parameters
You can create and modify material data using the Materials and the Material Definition dialog boxes. The material data can be saved to the model or saved to material data files that have a .mtl extension. The .mtl files are stored in the material library directory. Each file contains the name of the material and a set of material parameters that are identified by an ID and units information.
User-defined material parameters are parameters that you define by using the User Defined tab in the Material Definition dialog box. All other parameter values that you define through the Material Definition dialog box are stored as reserved parameters. If you define a user-defined parameter that has the same name as a reserved parameter, Creo Parametric issues a warning.
Note the following points about material parameters:
You can use the material parameter values in relations.
You can assign materials to family table instances by adding PTC_MATERIAL_NAME parameter to the family table.
You cannot designate material parameters except the PTC_MATERIAL_NAME parameter.
When you save a material, parameters with default values are saved only if you have changed the default value. Additionally, only parameters that are valid for a specified material type are saved, for example, the Orthotropic Young's Modulus is not saved for an isotropic material definition.