Creo Direct > References > Data Management > Workspace > Object Operations in the Workspace > Exchanging Units > About the Bidirectional Conversion of Parameter and Attribute Units
  
About the Bidirectional Conversion of Parameter and Attribute Units
You can propagate and map the units of Creo model parameters to the corresponding units of Windchill attributes while uploading models to Windchill. You can then display the units and the relevant unit systems, if any, in the Attributes section of the CAD Document Property Page (CDPP) and Edit Properties page of Windchill. You can also propagate these converted units back to the Creo application while downloading CAD models from Windchill servers and retrieving them in the Creo application. The units of Windchill attributes are implicitly mapped to the corresponding units of the Creo designated parameters.
The bidirectional mapping of the units of measures between the Creo application and Windchill are accurate even when you edit and update the parameters or the attributes and their values in either system. The mappings are explicit or implicit wherein the parameter names, their values, and units match the attribute names and values with units. You can store the unit systems of models without storing them as attributes on the model. This mapping enables search on the server for CAD models. The units information also enables you to accurately classify CAD data on the server.
Creo models have their system of units. The predefined systems of units in the Creo applications, such as MKS, CGS, and the FPS, define custom units and systems of units through preferences that you can set. However, the default system of units in Creo and Windchill are used to propagate and map units. The default system of units in Creo is Inch lbm Second (Creo Parametric Default). Windchill uses the SI units of measure.
When you add parameters to a model in a Creo application, parameters of type real number are assigned units. You can map the designated real number parameters with units to the corresponding attributes and their units of type, floating number with units. This is because only attributes of type, floating number with units, have units in Windchill and you cannot change this attribute type. For example, when you upload and check in to a server a model with a designated value of 254 cm assigned to a real number parameter, this parameter value of 254 cm is converted to the value of 100.0 in Windchill for the attribute of type, floating number with units.
If you edit this value in Windchill to 150.0 and download, check out, and retrieve the model in a Creo application, the value of 150.0 is converted to the value of 381.00000 cm for this designated parameter. While retrieving the model, if the parameters are without units due to a change in the attribute type, you can assign units for these parameters in the Creo application. However, you are notified when a parameter value without units is automatically assigned units because it modifies the file in the Creo application.
Additionally, there are no attribute types with units in Pro/INTRALINK. However, you can designate parameters with units to the attributes without units in Pro/INTRALINK. You can, therefore, update parameters without units to their unit-based definitions. Their conversion is based on the Creo model units.