# Yang files There are two classes of Yang files * Clixon yang files. * Mandatory: "Standard" yang files necessary for clixon lib/client/backend to run Both are always installed. If you want to change where the are installed, configure with: `--with-yang-installdir=DIR` The third (optional) is only installed if configure flag `--enable-optyang` is set. Further, the optional yang files are installed in `--with-opt-yang-installdir=DIR` if given, otherwise in the same dir as the mandatory.