AddAction

Add-actions are used by the server to determine where to place a node with respect to other nodes. They form an enumeration of integers which are represented by case objects being subclasses of this abstract class.

The following actions are known:

• 0 - addToHead
• 1 - addToTail
• 2 - addBefore
• 3 - addAfter
• 4 - addReplace