(In the context of structure contour editing)

A vertex of a structure contour or a line landmark. Same as control node; a controller on one of the HET system's printed circuit boards that is an embedded computer. HET Clinac subsystem controls are located on node control boards, including beam generation and monitoring (BGM), collimation (COLL), positioning unit (PU), couch, and so forth. The BGM node has subnodes for modulator (MOD), pulse-width modulation (PWM), and so forth.