Holds are recorded over 4 bars, a Hold will stop where the next chord is entered so if you enter the next chord on the 5th bar it should ring out over 4 bars. If you look in the RealTrack folder for the Holds folder and drop one in your DAW set to 80bpm you will see how they work. Also if you go into Tracks View and enable the Riff Edit button you can adjust the length of the Hold and right click it to adjust volume.