SUMMARY Non-ascii characters in XML attribute names need to be escaped. This is done in the method FileWriter::escape(). Unfortunately, this function is not fully unicode aware, leading to multiple code points being escaped to the same value. E.g. both "😃" and "⌘" are escaped as "_.0". This could lead to ambiguities if two category names just differ by one character that is mapped to "_.0". ADDITIONAL INFORMATION Some information on the issue can be found in the commit message for commit ac5370fb2492477606587278899df2300043c75b.