The Reply Log contains informational, warning, and error messages from Chimera. Error messages are in red and warnings are in blue italics. When IDLE is open, however, messages are sent there instead of to the Reply Log. See also the Messages preferences.
There are several ways to start the Reply Log, a tool in the Utilities category.
Clear erases the log. Copy copies just the selected portion so that it can be pasted into another application window, while Save brings up a dialog for saving the entire contents to a file. The log can be searched for a string of interest, and the Forward and Back buttons can be used to navigate between multiple occurrences of the string.
Close dismisses the Reply Log, and Help opens this manual page in a browser window.