$title  uses system.f? and compares with full file name (PUT4,SEQ=37)
file temp /temp.gms /;
putclose temp '$if NOT "' system.fp system.fn system.fe '" == "%system.fp%%system.fn%%system.fe%" $error not the same'
execute '=gams temp.gms lo=%GAMS.lo%';
abort$errorlevel 'gams program above failed';