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A fieldset is a collection of fields stored physically in GRIB files. Metview has many built-in features functions and operators to manipulate fieldsets, from simple arithmetic operators to vertical integrations through the atmosphere. Many of these operations are available from the icon-based user interface, all are available in the Macro language. The results can be stored on disk, or passed to other functions for further manipulation.
Most of these functions work on each gridpoint value of each field in the fieldset. For example, if we add 1 to a fieldset which contains 3 fields, this will return a new fieldset with 3 fields, the values of which are 1 greater than their respective input fields.
XXX diagram of how fieldset operations are done?
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