GRS knows two types of point lists: A tensor product point list which
equivalences a PIF point list containing an orthoProduct construct,
and an unstructured point list corresponding to a PIF point list containing
a valueList with point coordinates. Both point list types have their own
classes and are derived from a generic point list class, which is represented
by a value declaration class, and was already described on
page 
. The unstructured point list is fully represented by a value
definition class, and was discussed on page .
Tensor product point lists differ considerably from unstructured point lists,
since they take advantage of the regular arrangement of their individual
points, leading to a compact memory representation. Nevertheless, a large
variety of different grids can be represented, ranging from one-dimensional
grids to multi-dimensional grids with different topological and topographical
dimensions
.
The point list classes of GRS are prepared for the representation of
physical models too, because point coordinates are not limited to three
dimensions, and axis units may be non-spatial ones. Thus it is possible, for example, to define a
plasma etch rate of a flat unshadowed wafer dependent on the reactor pressure,
plasma frequency and reactor temperature in an unstructured or tensor
product point list object, and use the corresponding interpolation functions
to obtain etch rate values at arbitrary ``points''. In this case, the data
values are no longer called points, but referred to as point tuples
rather.