Item between old and new positions of module:engine/model/treewalker~ModelTreeWalker.
OptionallengthLength of the item. For 'elementStart' it is 1. For 'text' it is the length of the text. For 'elementEnd' it is undefined.
Next position of the iterator.
'elementStart' it is the first position inside the element. For all other types it is
the position after the item.'elementEnd' it is last position inside element. For all other types it is the position
before the item.Previous position of the iterator.
'elementEnd' it is the last position inside the element. For all other types it is the
position before the item.'elementStart' it is the first position inside the element. For all other types it is
the position after item.
Object returned by module:engine/model/treewalker~ModelTreeWalker when traversing tree model.