s := = s

Get/set the method used for extrapolation of zone-based variables.

This has no effect on gridpoint-based variables.

The available names are constant, average, inverse-distance-weighting, and polynomial. The default value is constant.

The extrapolation methods are used to determine values at the gridpoints of the zone. Then a weighting function is used to determine how values vary inside the zone.

Returns:s - the zone field extrapolation method name
Accepts:s - the zone field extrapolation method name. Keyword matching rules are used on assignment. If no match is found, an error will occur.