See https://office.wikimedia.org/w/index.php?diff=prev&oldid=327737 (private wiki)
I suspect that this was caused by repeatedly switching from wikitext to visual modes, but the visual editor doesn't support association lists, so the wikitext mode was the only way to get it done. Note particularly the table corruption (I didn't even click on the table, much less edit it) and the replacement of interlanguage links: w:de: became :en:de: