ABL supports a protocol to provide default mappings between native COM object method parameter and property values and the corresponding ABL data values. This mapping protocol supports many COM data types. You can override the default mapping by using a type specifier, as shown in the following table. For more information on mapping data types shown in the following table, see COM Object Data Type Mapping.

Table 1. Data-types for COM object methods and properties
Data-type specifier to override the default mapping ABL data type
CURRENCY DECIMAL
ERROR-CODE INTEGER
IUNKNOWN COM-HANDLE
FLOAT DECIMAL
SHORT INTEGER
UNSIGNED-BYTE INTEGER

Each of these data-type specifiers represents one of the base COM data types available for a method parameter or property. Each ABL data type represents the typical ABL data type that corresponds to the specified COM data type.

Data-type specifier options are necessary only for some method input parameters and property settings. Whether or not you must specify the AS datatype or any of the other type options (BY-POINTER or BY-VARIANT-POINTER) depends on the COM object method or property and the implementation of the COM object. You can also specify how a method parameter of any data type is passed using the mode options OUTPUT or INPUT-OUTPUT. Whether you use a mode option depends (in part) on how you plan to use the method parameter in your application. For more information on using data-type specifiers and mode options, see Specifying options for properties and method parameters, and COM Object Data Type Mapping.