1 through 7 are the numbers used to indicate the root of the chord. If you’re in the key of G, 1 is G.

Brings up a menu with choices for accidentals (flat, sharp, natural) to define a chord number.

Creates an inversion, or “slash chord.” First tap the chord number, then “x/y,” then the number of the bass note.

Creates a new line.

Creates a new section.

Phrase separator dot. Usually used to break up longer lines into more readable chunks, e.g. groups of four measures.

Inserts a space between chords or measures.

Ends a measure, underlining the measure by default.

Brings up a menu with options for “X” to signify a rest, and parentheses to wrap an implied chord.

Delete key.

Hides the keyboard.

2 through 13 are used to indicate chord qualities, sometimes in combination with “add” or “sus,” e.g. “sus4.”

Major 7.

Major. Not typically required (the absence of “minor” implies major), but sometimes it’s helpful to be explicit.

Minor.

Accidentals. Brings up a menu with choices for flat, sharp and natural, to define superscripted chord qualities.

Tap this key to bring up a menu with choices for “slash” and parentheses, sometimes used in more complex chords.

Brings up options for characters denoting augmented, half-diminished, diminished, m7b5, alt, etc.

Suspended.

Add, as in “add9,” etc.

Minor.