The nodes are used to describe the network elements which make up the mixtures and the divisions of streams. In a node, several branches are connected to form a single vein. If it is a mixer, the various branches join to form a single vein. The mass flow of the main vein is equal to the sum of those of branches, and the enthalpy balance is used to calculate the enthalpy and temperature of the mixture. If it is a divider, the main vein is divided into several branches, whose flow rates must be calculated. Their distribution between the branches is taken proportional to the "flowfactor" specified by the user. The temperature and enthalpy are of course conserved.