On Thu, 16 Oct 2014, Sven Schreiber wrote:

> I remembered that join only works with .csv files, as duly mentioned in > the docs. Then all worked nicely; however, from a little distance now I > must say that this feels a little "lame", gretl not being able to use > its own files!? That could be implemented. It would take a while: while we can easily find our way around in our own files, a lot of the code was initially tailored to the CSV assumption. I think we took it for granted that the principal real-world use of join would be with files from third-party sources.