Microsoft Excel 2007 contains many exciting new features, and XLL+ 6 supports them fully.
With XLL+ 6, you can mark an add-in function as thread-safe, and it will be available to be used in a multi-threaded recalculation under Excel 2007. On a dual- or quad-core processor, or on a machine with multiple processors, this can lead to a substantial performance improvement.
All the XLL+ run-time classes that are available for use from add-in functions are now thread-safe.
Excel 2007 increases the maximum size of a worksheet, from 65536 rows x 256 columns to 1048576 rows x 16384 columns. XLL+ classes support the new sizes, as well as continuing to work correctly with the older versions of Excel.
Excel 2007 works natively with Unicode strings. This means that all the text associated with your function can be in the character set of your native language, including the function name, argument names and all help text.
XLL+ 6 fully supports Unicode, both in the tools and in the run-time library. In addition, the error text returned by XLL+ add-in functions can now be localized, so that it appears in the language of the spreadheet user.
Excel 2007 supports up to 255 arguments to an add-in function (previous versions allowed only 30 arguments). XLL+ 6 supports the new limit, and also offers new and powerful features to help you group multiple arguments, to support older versions of Excel.
String values can now be up to 32,767 characters long (previous versions supported only 255 characters).
The add-ins you build with XLL+ 6 will work under both Excel 2007 and older versions of Excel. Any Excel 2007 features that your functions use will not be available under when your add-in is opened with Excel 2003 or below.
The XLL+ framework will make sure that each function is registered correctly under either environment, and will handle the differences between the two, so that your code can be platform-independent.