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The Mesh section contains all the mesh data, including nodal coordinates and element connectivity. It has the following sub-sections:

At least one Nodes must be defined and one Elements section. The other sections are optional. The NodeSet, Edge, Surface, DiscreteSet, ElementSet, and SurfacePair sections define sets of nodes, edges, facets, discrete elements, elements, and surface pairs, respectively, and can be referenced by other sections of the model file. For instsance, boundary conditions can be defined by referencing the sets to which the boundary condition will be applied.