This read-write string is appended to the names of log files the Clarent Gatekeeper creates, letting an admin tag log files with an identifying suffix. It's useful for distinguishing log files from a particular gatekeeper instance when multiple gatekeepers write to a shared log location. For example, setting gkLogFileAppendString to "_gk1" produces log file names ending in "_gk1" so they can be told apart from another gatekeeper's logs.