The function of this data category is to define a table of coordinate positions on the structure or fixed in space, referred to in later data categories, e.g. Element Topology (Data Category 2) used for modeling the structure. These positions are referred to in the documentation as nodes. A node is defined by an integer number (called a node number) and three Cartesian coordinates which are associated with this number.

The node number is used only as an index to the values of the coordinate positions and therefore may be any numbers which are convenient to the user. Node numbers do not have to be in any order, sequenced, or referenced by another data category.

Node numbers must be unique.

Although you may find that using a series of random integers is quite valid, the hydrodynamic and hydrostatic modeling of the structure in Data Category 2 can be made considerably easier by a logical ordering of the node numbers.

For 32-bit Aqwa, there can be up to 30000 nodes explicitly defined, or 60000 if one symmetry data record is used, or 120000 if two symmetry data records are used. For 64-bit Aqwa, there can be up to 60000 nodes explicitly defined, or 120000 if one symmetry data record is used, or 240000 if two symmetry data records are used.

When The STRC Data Record - Coordinate Structure Association (STRC) is not used, the coordinate positions in this data category are not specifically associated with any one structure nor with any one element within that structure. This means that many elements may reference the same node number and several structures may also reference the same node number. This does not mean that the structures are joined together at a node, but that the structures are completely independent unless specified otherwise (for example, Data Category 12 (Constraints) and Data Category 14 (Mooring Lines)). When a structure moves, the node moves with the structure.

When used, The STRC Data Record - Coordinate Structure Association (STRC) provides a means to associate particular nodes with individual structures.