When you save a generic part and its features and dimensions in a Family Table by choosing Save from the File menu, the system creates or updates an external generic modelname.ptd file. At that moment, the modelname.ptd file contains the same Family Table information as is stored internally (within the part database).

You can edit a Family Table outside of Creo Parametric, using any text editor from the operating system level to edit the .ptd file. Any modifications you make to the .ptd file are not automatically copied to the Family Table within Creo Parametric. For example, if you delete an instance during the .ptd file edit, when you later retrieve the model in Creo Parametric, the system detects that the table is missing an entry and asks you whether you want to similarly modify the Family Table in Creo Parametric.

You can also edit the modelname.ptd file in a different window outside of Creo Parametric while working with the part containing the Family Table in Creo Parametric. In this case, if you save the part by choosing Save from the File menu, the internally stored Family Table takes precedence over the external modelname.ptd file, if that external file exists in the current directory.

When you retrieve a part containing a Family Table while an external modelname.ptd file exists in the current directory, the external file takes precedence over the internally stored table.

Creo Parametric no longer reads and writes to .ptd files by default. You can now use the configuration file option read_famtab_file_on_retrieve to choose whether you want Creo Parametric to read and write to .ptd files.