1.8.6.2 In parameters

For in parameters:

• A parameter with the string attribute will be converted to a Lisp string. The string should not be destructively modified by the body.
• A parameter of COM type BSTR will be converted to a Lisp string. The string should not be destructively modified by the body.
• A parameter of COM type VARIANT* will be converted to a Lisp object according to the VT code in the variant (see Automation types, VT codes and their corresponding Lisp types).
• A parameter of COM type SAFEARRAY( type ) or SAFEARRAY( type )* will be converted to a Lisp array. The elements of type type are converted as in Automation types, VT codes and their corresponding Lisp types.
• A parameter of COM type VARIANT_BOOL will be converted to nil (for zero) or t (for any other value). Note that a parameter of type BOOL will be converted to an integer because type libraries provide no way to distinguish this case from the primitive integer type.
• A parameter whose type is an array type or a pointer type with a size_is attribute will be converted to a temporary Lisp array. The Lisp array might have dynamic extent.
• Otherwise, the value is converted to a Lisp value using the FLI according to the mapping of types defined in FLI types.

LispWorks COM/Automation User Guide and Reference Manual - 19 Dec 2011