containing @code{(@var{step} . @var{alter})} or
@code{((@var{octave} . @var{step}) . @var{alter})}, where @var{step}
is a number in the range 0 to@tie{}6 and @var{alter} a fraction,
denoting alteration. For alterations, use symbols, e.g.
containing @code{(@var{step} . @var{alter})} or
@code{((@var{octave} . @var{step}) . @var{alter})}, where @var{step}
is a number in the range 0 to@tie{}6 and @var{alter} a fraction,
denoting alteration. For alterations, use symbols, e.g.