The base of the finite element model is modelled as a beam, so that bending (flexure) and isostatic equilibrium (buoyancy - balance of forces as though over an enclosed liquid) can be calculated. It can either be a single beam or a broken beam. A broken beam will allow a discontinuity at the break. The point where the beam is broken is called the singularity. In the case of a broken beam, we say there are 2 beams. Beam 1 is the RIGHT-hand beam (has node numbers > singularity) and is the active beam. Beam 2 is the LEFT-hand beam. Each beam has an end1 at the left-hand end, and an end2 at the right-hand end. The variable 'nbreak' is the node number of the singularity and is located at end2 of beam2 (beam nodes are numbered 1 -> # eulerian nodes in horizontal (y) direction). The displacement of end2 of beam2 can be slave to that of end1 of beam1, so any point load must be located >nbreak (usually at nbreak+1). Each end of each beam has its own degree-of-freedom (dof) specifications. Dof1 is a deflection or force, dof2 is a rotation or moment/torque:

dof1 = 0 -> imposed deflection
dof2 = 0 -> imposed rotation (slope)
dof1 = 1 -> imposed force
dof2 = 1 -> imposed moment/torque

A dof=-1 can be specified for dof1 of end2 of beam2, and indicates that it is a slave to end1 of beam1.