Command extensions enable extra features in NT shells.
By default command extensions are enabled.
However, to be absolutely sure that they are, either use SETLOCAL ENABLEEXTENSIONS within your NT shell scripts (batch files) or execute those scripts using CMD /X.
Likewise, you may disable command extensions using SETLOCAL DISABLEEXTENSIONS or CMD /Y.
Read my SETLOCAL page if you intend to use SETLOCAL extension switches.