Limitations on CustomData property of ConnectionString

Is there any place where I can find detailed documentation for the CustomDataproperty of ConnectionString for Analysis Services?

I've read MSDN Documentation for

1. Connection String Properties (Analysis Services)
2. AdomdConnection.ConnectionString Property

Both of the links do not mention anything at all about CustomData.

The information I need is:

• What are the restrictions on CustomData parameter with respect to its length and datatype?
• Can I pass a formatted string, that I can process later maybe through an assembly in cube, as a parameter inCustomData?

Regards,
Akshay