REFERENCE_GRID
This is part of the gridtools module

Setup a constant grid by either reading values from a file or definining a function in input

Examples
Glossary of keywords and components
Description of components

By default the value of the calculated quantity can be referenced elsewhere in the input file by using the label of the action. Alternatively this Action can be used to calculate the following quantities by employing the keywords listed below. These quantities can be referenced elsewhere in the input by using this Action's label followed by a dot and the name of the quantity required from the list below.

Quantity Description
.#!value the constant function on the grid that was specified in input
Compulsory keywords
GRID_MIN ( default=auto ) the lower bounds for the grid
GRID_MAX ( default=auto ) the upper bounds for the grid
PERIODIC are the grid directions periodic
FILE the name of the file that contains the reference data
VALUE the name of the value that should be read from the grid
Options
FUNC the function to compute on the grid
GRID_BIN the number of bins for the grid
GRID_SPACING the approximate grid spacing (to be used as an alternative or together with GRID_BIN)
VAR the names to give each of the grid directions in the function. If you have up to three grid coordinates in your function you can use x, y and z to refer to them. Otherwise you must use this flag to give your variables names.