Is impersonating breaking the 4th Buddhist precept?

Most if not all of us had used alias, pseudonym or avatar at one time or another while interacting with others on the Internet. There may be good reasons for doing so such as the desire to protect our privacy, fear of intimidation or to criticize people in power without fear of retaliation. Of course, there could be less than noble reasons as well. Is the use of alias, pseudonym or avatar i.e. impersonation considered breaking the 4th Buddhist precept of lying? If using an alias, pseudonym or avatar is alright then why stop at one? What is wrong with using more than one impersonating identity? If a person created multiple accounts in a forum (like the one I am writing in) and there is no explicit rule forbidding it, is it alright? Appreciate if answers would cover the subject from a Buddhist perspective.