Regarding the bonus: from what I understand from the documentation, concatenating libnames across multiple data libraries will work just fine as long as there are not datasets with the same name in more than one library? The documentation on which rules apply to which datasets seems well documented, if not that intuitive; on my part I would find it much more difficult to remember what applies when using the concatenation; I think individual calls to the macro would be slower, but more likely to do what I intended? Especially if there were datasets with the same names? Is there an easy way to have SAS tell me if there are duplicate dataset names in a concatenated library?