What is UFO warning: invalid complex declaration of input parameter

According to page 10 of the official UFO document (https://arxiv.org/pdf/1108.2040.pdf): "In the UFO format, the external parameters are all taken to be real and the type attribute of the Parameter class must be set to the value ’real’. Therefore, complex numbers will have to be split into their real and imaginary parts."

While it would be easy to extent O'Mega's UFO code generator to support complex valued external parameters, it is very likely that interfaces to external programs with not be able to take advantage. Therefore the warning appears to be the better approach.