**Not mandatory.** Implemented if needed.

Response for event [CLASS1.PROTOCOL, Type=40 (Get event interest)](./class1.protocol.md#type40). The node report all events it is interested in. 

 | Data byte | Description | 
 | :---------: | ----------- | 
 | 0 | Index | 
 | 1 | class bit 9 (see table) | 
 | 2 | class 1 | 
 | 3 | type 1 | 
 | 4 | class 2 | 
 | 5 | type 2 | 
 | 6 | class 3 | 
 | 7 | type 3 | 

 | Bit | Description | 
 | :---: | ----------- | 
 | 0 | Bit 9 for class 1 | 
 | 1 | Bit 9 for class 2 | 
 | 2 | Bit 9 for class 3 | 
 | 3 | All Type 1 is recognized (set type to zero). | 
 | 4 | All Type 2 is recognized (set type to zero). | 
 | 5 | All Type 3 is recognized (set type to zero). | 
 | 6 | 0 | 
 | 7 | 0 | 

A node that is interested in everything just send a [CLASS1.PROTOCOL, Type=41 (Get event interest response)](./class1.protocol.md#type41) with no data if asked to provide that information.

Nodes that want to specify events of interest fill them in. If all types of a class should be recognized set the corresponding bit in byte 1 and the related type to zero.

A maximum of 255 frames (index = 0-254) may be sent. 

Fill unused pairs with zero.

A **level II node** respond by sending [CLASS2.PROTOCOL, Type=41 (Get event interest response)](./class2.protocol.md#type41)
