Guitar chord transposer

Only chord tokens move: a note letter with one accidental, a known quality (m, maj7, sus4, add9, dim, aug and the number extensions), and an optional slash bass. Everything else passes through untouched, whitespace included. The one honest exception is bare note letters: the word A at the start of a lyric line is also an A chord, and the tool cannot tell them apart, so keep chord lines and lyric lines separate when a lyric starts with A through G. Equal-temperament spelling only; the tool does not suggest capo positions or reformat your chart.