TRACE0 is similar to TRACE, and is one variant of a group of trace macros that you can use for debug output. The group includes:
TRACE0 - Takes a format string (Only) and can be used for simple text messages which are dumped to afxDump
TRACE1 - Takes a format string plus one argument (one variable which is dumped to afxDump)
TRACE2 - Takes a format string plus two arguments (two variables which are dumped to afxDump)
TRACE3 - Takes a format string plus three arguments (three variables which are dumped to afxDump)
TRACE0 does nothing if you have compiled a release version of your application. As with TRACE, it only dumps data to afxDump if you have compiled a debug version of your application.