# 6.7. Explicitly Computing Derived Quantities

    BEGIN DERIVED OUTPUT
      COMPUTE AND STORE VARIABLE =
        <string>derived_quantity_name
    END DERIVED OUTPUT

The above command block is used to explicitly compute and store a derived quantity into an internal field. This is useful if the field is needed by an outside capability such as a transfer or error estimation.

For example, to use a derived quantity in a transfer, a `DERIVED OUTPUT` command block must be used. For instance, to transfer the von Mises stress norm:

    BEGIN DERIVED OUTPUT
      COMPUTE AND STORE VARIABLE = von_mises
    END DERIVED OUTPUT

Tables Table 9.13 through Table 9.19 in Section 9 list element variables available for different types of elements. Variables that are only computed at user request are designated with a `yes` in the `Derived` column of these tables. These are the quantities that must be listed in a `BEGIN DERIVED OUTPUT` command block if they are to be transferred during a coupled analysis.