Command Extensions are enabled by default. You may also disable extensions for a particular invocation by using the /E:OFF ...

Command Extensions are enabled by default.  You may also disable extensions for a particular invocation by using the /E:OFF switch.  You can enable or disable extensions for all invocations of CMD.EXE on a machine and/or user logon session by setting either or both of the following REG_DWORD values in the registry using REGEDIT.EXE:      HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\EnableExtensions          and/or      HKEY_CURRENT_USER\Software\Microsoft\Command Processor\EnableExtensions  to either 0x1 or 0x0.  The user specific setting takes precedence over the machine setting.  The command line switches take precedence over the registry settings.  The command extensions involve changes and/or additions to the following commands:      DEL or ERASE     COLOR     CD or CHDIR     MD or MKDIR     PROMPT     PUSHD     POPD     SET     SETLOCAL     ENDLOCAL     IF     FOR     CALL     SHIFT     GOTO     START (also includes changes to external command invocation)     ASSOC     FTYPE  To get specific details, type commandname /? to view the specifics.