Uwe-
URL match=http://en.wikipedia.org/w/ Username=myuserid Password=mypasswd
Then I thought this would be enough for any wiki site in english, like http://meta.wikipedia.org which is wrong as I understand now.
No, but if your user name and password are the same across all Wikipedias, using
URL match=wikipedia.org
should work for all Wikipedias. If you only intend to edit Wikimedia wikis and they all have the same username and password, even
URL match=.org
should do the trick. The help page already states this, but please do edit it if you think it could be made clearer.
Best,
Erik