An N.C. (no chord) makes the chordal instruments drop out for the length of the bar. The drums keep playing. Type n, or use the N.C. button. To remove it, tap the highlighted N.C. button again; on Mac and Windows you can also delete the n from the chord entry box.

 

Add the word Break as staff text and the drums hit beat one and stop, staying silent until the next double barline. Combine a Break with an N.C. in the same bar for complete silence, which is how you write a pickup measure. For staff text, see Add text to chart.

 

For more, see Chord symbols and notation on the iReal Pro website.