它这个是说，你按住function键不放，然后这时候MIDI琴键的第二个八度就变成数字键来用了。也就是说，比如你想输入125，就按住左侧的Function键，然后依次敲琴键上第二个八度的C#、D、F。明白？
If you hold down one of the function buttons and then press the keys of the CMK 149, MIDI note data will not be transmitted because the second octave of the keyboard is activated as a numeric entry field to enter the values to change the chosen parameters.