Classificatienode cannot be deleted...Error: 
This classification node cannot be deleted because it contains article group classifications. 
Explanation: 
The own classification consists of a maximum of 4 layers. If you delete a 4th classification layer which still has articles classified under it, an error message is shown on the screen. 
In other words, deleting a classification layer on the 4th level is only possible if all the underlying articles have first been placed in other classifications. 
Solution: 
First classify all underlying articles in another classification and only then remove the 4th classification level. 
The example below shows the same action, but with a 3rd level example. 
Wrong: Under the 3rd level classification layer "Codes" is a fourth layer: "Codes" present 
![]() Right: The 4th classification layer "Codes" has been removed first, after which the third layer, classfication layer "Codes" can be removed. 
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