A joint restraint applied to a model is described in the Multiframe Automation interface as the Restraint object.  Similarly, a joint spring and a joint mass are described within the interface using the Spring and NodeMass objects.  These objects contain the properties of the different items in a frame such as the node to which the spring/restraint/mass is applied or its index within the parent collection contained by the Frame object.

Each of these objects includes a Label property that may be used to identify the item or contain a string of user-defined information.  This property is only available via the automation interface and cannot be edited or viewed via the user interface of the current version of Multiframe.