6 The parameter can be defined in form *variable=expression*.
8 To create a parameter in the active partset or part:
10 #. select in the Main Menu *Part - > Parameter* item or
11 #. click **Parameter** button in the toolbar:
13 .. image:: images/expression.png
19 The following property panel appears.
21 .. image:: images/parameter.png
25 Parameter property panel
29 - .. image:: images/expression.png
31 defines parameter name following the naming rules of the python language for variables;
33 - panel **Expression** evaluates the expression input manually as a real number by python *eval()* function. In the simplest case an expression is a real number. Some standard python modules (like math) are imported by default before evaluation.
35 - **Comment** contains any text. This field is optional.
38 The property panel checks validity of the expression. For an invalid expression **Apply** button is disabled and an error message generated by python interpreter during the evaluation is shown in the status bar and in pop-up of **Apply** button.
40 **TUI Command**: *model.addParameter(Part_doc, Name, Value, Comment)*
42 **Arguments**: 1 Part + 1 string + 1 value + 1 string
44 **See Also** a sample TUI Script of a :ref:`tui_parameterFeature` operation.
49 The created parameter and its current value are displayed in the Object Browser, in a special section **Parameters**.
51 .. image:: images/object_browser_parameter.png
55 **Parameter** in object browser