{AB1 => 100, NN => 200, XYZ => 400}
{AB1 => 100, XYZ => 400, MM => 300}

##</code><code>##

"AB1","NN","XYZ","MM"
"100","200","400",""
"100","","400","300"

##</code><code>##

AB1   NN       XYZ   MM
100   200      400   undef
100   undef    400   300