An important rhythm technique used in many styles of music is the Percussive Strum. This is achieved by forming a chord shape with the left hand and placing it on the strings, but not pressed down on the frets. A percussive strum is indicated by using an X in place of a notehead.
This technique can be applied to anything from a two note power chord to a bar chord covering all six strings. Listen to the following example on the recording to hear what the percussive strum should sound like when applied to Root 5 power chords.