Am 20.01.2016 um 12:04 schrieb Paul Smith:
Thanks, Uwe. There was an error with\@ifundefined{extrarowheight} {\usepackage{array}}{}
Yes, sorry, this code can only be used in the document preamble.
but after having removed that, it works perfectly. I mean, it suffices to use \setlength{\extrarowheight}{2pt} and \setlength{\extrarowheight}{0pt}
Fine. thanks and regards Uwe