String illegal escape charcter

While answering one of the question, I came across this interesting situation. If I have string like the following, Netbeans does not complain that it's an `illegal start of expression`. ``` String temp="\19825655."; ``` As soon as I remove '1' it complains that it's an `illegal start of expression`. ``` String temp="\9825655."; ``` couldn't figure out the reason for this behavior. Any input would be appreciated. Observation: It seems `\9` and `\8` has special meaning. Only for `\9` and `\8` I am getting `illegal start of expression`. All other combinations it is not complaining.