About Inkscape extensions in general

Extension calls are possible in different ways. You may find some description at http://wiki.inkscape.org/wiki/index.php/Extension_requirements. Inkscape can run extension from a lot of different interpreters and executors like Python, Ruby, Perl, binary executables, bash scripts and so on.

The "..." dots indicator in Inkscape user interface (menus)

Please note that extensions with "..." indicate the extension will have some GUI / menu to use. Extensions with out will perform action directly on current selection or the whole document!