You must first have one or more nodes selected, then use the Save Nodes As Clip File option from the File menu, or right-click on one of the selected nodes and choose the same option. When you want to add a clip back in, use Insert Clip File from the File menu. Note that you will need to manually reconnect it to any other nodes in the scene to get it to work once inserted. There is no way for the program to know exactly how to connect arbitrary node clips so this must be done manually.
- Oshyan