After that it operates just like the f() function, with xLiteReturn used to return a value to the calling statement.

Having returned, the xLteWorkbookFunction closes the called workbook (without saving).

My original use case for this functionality was to allow me to modularise xLite activities. So, for example, if building a dimensional model I could use a separate workbook for each dimension; isolating the dimension specific ETL logic and allowing for finer control over testing, and when in production, the run sequence for such logic (e.g. time dimension might run once a year, customer dimension code  every week).

The try it out, see the test_call_workbook_function.xls (there's also an .xlsm version) in the latest release ...