Hi Ravichand,
We have three types of nodes
Model Node - Only Model Attribute possible
Mixed Node - Model and Value Attributes possible
Value Node - Only Value Attributes possible
When a value attribute is added to Model node it turn into a Mixed Node. You cannot turn a Value Node into a Mixed Node.
To store the values it depends on how you implement it. You can write your own API's to save the data required.
Regards
Vinod