Description and storage of {@linkplain org.opengis.parameter.ParameterValue parameter values}. The first two paragraphs below are adapted from OpenGIS® Spatial Referencing by Coordinates (Topic 2) specification.

Most {@linkplain org.opengis.parameter.ParameterValue parameter values} are numeric, but for some operation methods, notably those implementing a grid interpolation algorithm, the parameter value could be a file name and location (this may be a URI). An example is the coordinate transformation from NAD 27 to NAD 83 in the USA; depending on the locations of the points to be transformed, one of a series of grid files should be used.

Some operation methods may require a large number of coordinate operation parameters. Also, some operation methods require that groups of parameters be repeatable as a group. In such cases, it is helpful to group related parameters in {@linkplain org.opengis.parameter.ParameterDescriptorGroup parameter groups}. Two or more parameter groups are then associated with a particular operation method, and each parameter group consists of a set of {@linkplain org.opengis.parameter.ParameterDescriptor operation parameters}, or other, nested parameter groups. This way of modelling is not mandatory; all coordinate operation parameters may be assigned directly to the coordinate operation method.