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It's quite simple. Adapt To Type will pass the LabVIEW native datatype to the shared library. This means it will pass a cluster as its structure pointer to the shared library for instance. The option yous see to choose between Handles by Value vs. Pointers to Handles only applies to the case where the parameter itself is a LabVIEW handle (String and Arrays), nothing else! It has no influence on embedded handles inside a cluster for instance. And it has no influence on any other LabVIEW datatype passed with the Adapt to Type configuration. I think that all said the meaning is simply understood. Basically it makes that your LStrHandle (or whatever Array type you have connected to the parameter) is either passed as LStrHandle string or LStrHandle *string. This has various implications. A Handle param parameter will always be passed into the function as a valid handle even when it contains 0 elements. A Handle *param value can be actually a NULL handle for an empty handle and your code better is prepared to account for that by making sure the handle is properly resized or allocated depending on that. The function NumericArrayResize() will properly handle both cases for you. Array Data Pointer will pass the pointer to the actual data portion inside the handle to the shared library. Note that this only really makes sense for datatypes where you will also pass in the actual lenght of the array to the shared library function as LabVIEW will NOT append a zero terminating character to a string for instance, so the library would otherwise have no idea how long the string array really is. The last one "Interface to Data" supposedly passes the interface pointer to the internal LabVIEW data object. This is analogous to a Variant but not the same. Supposedly you can then work on the data from within your C code with the interface as documented in ILVDataInterface.h. This is an object oriented interface based on the Windows COM specification but as it seems implemented in a LabVIEW platform independent way. Very powerful for automatic adapting C interfaces, that might work fully polymorphic if there wasn't the issue that you still can't have LabVIEW VIs that support such a template like approach directly.