The special orthoProduct construct was introduced to support tensor product grids in PIF, which significantly enhances the efficiency of storing tensor product grids while preserving its advantageous structure. The PIF orthoProduct grid has an origin point, may have different topological and topographical dimensions and each dimension may have a different base vector. Conforming to the PIF syntax, the number of supported dimensions is in principle infinite. The example Fig. 6.14 shows a tensor product grid of topological dimension two lying in three-dimensional space. This capability is needed e.g. to describe distributed boundary conditions of a three-dimensional device.
While reading and writing of tensor product grids is directly supported by the PAL, the GRS (Grid Support) high-level library see Section 7.1 provides an in-memory representation too, which is used for linear and higher-order interpolation of attributes defined on those grids.