Snap node method
The Snap node method snaps graphical elements onto existing nodes. You can also use it to snap together nodes to form new features after other nodes have been undone or deleted.
To use this method, tap 
and then tap the node on the map.
The Snap node method is also a convenient way to add text adjacent to a number of nodes or graphical items. If the position of a node is recalculated, the text moves with the node.
