Wouldn't the NodeId property help you? do you still need a custom property?
Can you give more specific details on whether this increment is required on a specific branch of the hierarchy or on the whole of it.
To me it looks like NodeId can be used, if not please help me understand why it cant be utilized.
thank you for your fast response.
Unfortunately the NodeID can not be used. Yes it is an unique identifier but is used "version wide". When adding a node in hierarchy A the node will have the NodeID 10, when adding a node in hierarchy B the node will have the NodeID 11.
What I basically need is a sequence or ID that is only used for one level as you can see in my example above.
Another example could be: We have a node that contains 3000 different products. When adding a product, the product ID should be automatically be set to 3001. This way it is very easy to filter throught products, for example "Show me products where ID between 100 and 150".
Thanks in advance!