During the last few days, I've seen some members changing the current language when replying to a thread. Those should know that there is a proper etiquette to take in consideration when doing so. This is taking from Help - Reply to a message:

Answer a message in the same language

Do not answer a message in a different language than the one the message was posted. If the message was posted in English, then English should be used for the entire thread. As for the most used language in the Universal Thread, English will be accepted at any time.

By doing so, you are cutting that thread from that level to anyone else who won't understand what you are saying. This can also be irritating for some members, especially the one who made the last reply before the cut, as it could be seen as a way to tell something to someone about that member so he won't understand what you are saying.

If the purpose of doing so is to cut off from the main topic and talk about something else, a new thread should be created either from the same forum, if technical, or in Chatter if non technical.

If the purpose is to follow up on the thread in a different language, if that is really what you want, switch to the proper forum for the language you want and create a new thread in there.

If the purpose is to follow up on the thread in the same forum, do so in the same language.

By doing so, you are cutting off the thread to any potential members who would like to participate in it, is irritating members who already participated on it and, most of all, especially when being done in the English forum, a great percentage of members don't understand anything about what you are writting.

Please, respect that. We didn't write it in there for nothing. :)