How to protect a symbol in libreoffice formula?

Often in libreoffice formula special symbols like brackets or equal sign have some special meaning, and using them in the “wrong” place breaks the formula layout.

Is there a way to protect a symbol (“escape”) from being interpreted differently than a simple character ?

I tried \ or % but they don’t work.

It seems the answer is “no”.
You can always quote the offending characters (e.g. “+”) but this not always leads to the desired results, e.g. you may need to add the “italic” keyword.

An other trick I found in the meantime is to use empty curly braces for binary operators when one of the two operators is not needed.