Repeat for each system (ISYS) N=1, NSYS, in order

It should be noted that all structural elements and constraints formulations assumes that number of translational degrees of freedom in a structure system equals NSD, while the rest (NDOF-NSD) are rotational degrees of freedom, where NDOF is number of degrees of freedom per node.1-5 System identification number(ISYS(1,N)): EQ.1, STRUCTURE, uses translational and rotational Ds.O.F EQ.2, SOIL, uses translational and rotational Ds.O.F EQ.3, FLUID, uses velocity potential Ds.O.F EQ.3, FSURF, uses velocity potential and free surface elevation Ds.O.F 6-10 System's start node (ISYS(2,N)) 11-15 System's end node (ISYS(3,N)) 16-20 System's number of degrees of freedom per node (ISYS(4,N)) 21-25 System node increment