Hello Peter, thanks for your response. I get your point that the POINTCLOUD command works more similarly to a macro CALL, pointing to an specific data file within the library with .gspc extension. In the GDL reference guide it does not say that the string expresion must be constant: “data_file_name: the name of the loaded library part containing the point cloud data. Must be a string expression.”
Macro CALL command does work with variables as the target. And so should the POINTCLOUD command. I think the way the default object generated from Pointclouds at the moment is very limited, and what I am developing is an object to handle Pointclouds within Archicad in a more useful way for the user. But I am currently stuck with having to edit the object in the GDL editor, just to change the target .gspc libray part of the POINTCOULD command.