The Variant Change Clause modifies or removes a variant
    definition within a variants definition.

    When you change or add a variant definition to a record
    definition, you must tell CDO its position. To indicate the
    position of a variant definition to CDO, you use the VARIANT and
    END VARIANT keywords, so each preceding variant is referenced.

    If you specify a conditional expression, the expression must be
    valid for the layered product that uses your definition. If one
    definition uses an expression, each definition in the variant
    definition must use an expression. Each expression in the Variant
    Change Clause must be unique.

    To add a definition to a variants or variant definition, use
    the Variant Change Clause to specify the variants or variant
    you want to modify. Then use the DEFINE keyword of the Record
    Change Clause and the appropriate clause for the type of entity
    definition you are adding.

                                   NOTE

       You must include a structure definition for each variant
       contained in a CDO record if developing a new application
       that will use a 3GL language and DIGITAL DATATRIEVE.

    For example, to add a field or record definition to the variants
    or variant definition, use the Included Name Change Clause.
    To create a structure definition in the variants or variant
    definition, use the Structure Clause.

    To create another variant or variant definition in the variants
    or variant definition, use the Variant Change Clause.

    To remove a field, record, or structure definition from a
    variants or variant definition, use the Variant Change Clause
    or the Variants Change Clause to specify the variants or variant
    definition you are changing. Then remove the field, record, or
    structure definition by specifying the DELETE keyword of the
    Record Change Clause and the definition name.

    To remove a variant definition, use the NOVARIANT keyword of
    the Variants Change Clause to specify the definitions you are
    removing.

    When you add a new definition it becomes the last definition in a
    variant definition.