How to export a simulink bus object to a previous version?

Opening a mat file created in matlab 2016b which contains a Simulink bus object in a previous version of matlab (2011b) I obtain the following warning: Warning: Variable (* name of the bus object *) originally saved as a Simulink.Bus cannot be instantiated as an object and will be read in as a uint32. Is there any procedure or command to save a bus to be compatible with a previous matlab version (as is already for models)?

[Frieder]

I am facing the same problem. It is possible to save the busdefinition as an m-script by using:

 matlab.io.saveVariablesToScript(filename)

but I need to save as mat-file. Also the m-script is not backward compatible because of the new "DocUnits" property. You need to modify the script after saving.