[[RF.Spice A/D]] has unlimited levels of undo and redo. To undo any changes to the schematic, use the keyboard shortcut {{key|Ctrl+Z}. The redo any undone changes, use the keyboard shortcut {{key|Ctrl+Y}}.
[[File:b2MAN_Fig36.png|thumb|400px| Node numbers in a schematic.]]
<b>Naming and Numbering Nodes</b>
Every node in your circuit has a unique number or name. <b>Node 0 is always reserved for the Ground</b>. To display the node numbers or names, click the "Show Node Names" button of the [[Schematic toolbar|Schematic Toolbar]] or use the keyboard shortcut {{key|Ctrl+Alt+N}} or check the Nodes items from the View > Show menu.
Nodes that are connected to each other via a wire get the same node number or name, and so does their connecting wire. Markers can be used to name a node or explicitly set a node number. Place the marker on a node and double-click on it to access its properties. Type in a name or number for the marker and the wire will take on the markerâs name or number. Note that you can place two markers on two different nodes in your schematic with the same name. In this case, you indeed connect these nodes without an explicit wire.
Node names and numbers can also be controlled by either right clicking on the wire and selecting rename node/wire, or double clicking on the node name itself when node names are enabled.
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[[File:b2MAN_Fig36.png|thumb|left|480px| Node numbers in a schematic.]]
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<b>Combiners, Splitters and Rippers</b>