Begins localization of environment changes in a batch file. Environment changes made after SETLOCAL has been issued are local to the batch file. ENDLOCAL must be issued to restore the previous settings. SETLOCAL If Command Extensions are enabled SETLOCAL changes as follows: SETLOCAL batch command now accepts an optional argument, which can be either ENABLEEXTENSIONS or DISABLEEXTENSIONS. This will enable or disable the Command process extensions until the matching ENDLOCAL command, regardless of their setting prior to the SETLOCAL command. The SETLOCAL command will set the ERRORLEVEL value if given an argument. It will be zero if one of the two valid arguments is given and one otherwise. You can use this in batch scripts to determine if the extensions are available, using the following technique: VERIFY OTHER 2>nul SETLOCAL ENABLEEXTENSIONS IF ERRORLEVEL 1 echo Unable to enable extensions This works because on old versions of CMD.EXE, SETLOCAL does NOT set the ERRORLEVEL value. The VERIFY command with a bad argument initializes the ERRORLEVEL value to a non-zero value.