Each bar is divided into cells, one per beat, and where a chord sits inside the bar is what tells the player how long it lasts. The player reads whole notes, half notes, and quarter notes, plus dotted quarters in 3/4. If the chords are bunched together so their lengths are ambiguous, it cannot build the audio and shows an error.

 

Leading blank beats are skipped rather than counted, so a chord written on beat three of an otherwise empty bar sounds on beat one. Fill those beats with slashes to hold the previous chord. Entirely blank measures are ignored too, including the space before a second ending that starts partway along a system: write a % there to repeat the previous bar.

 

Error messages. Pressing Play builds the audio first, so a problem appears as a message naming the bar. That number counts every bar the player passes through, repeats included. With a repeated 8-bar A section and then a B section, an error in bar 18 is the second bar of B (8 + 8, then 2).

 

For the full guide, see Chart layout and spacing on the iReal Pro website.