preferred_name: cytosine(out) + H(+)(out) => cytosine(in) + H(+)(in)
preferred_name_lc: cytosine(out) + h(+)(out) => cytosine(in) + h(+)(in)
label: cytosine(out) + H(+)(out) => cytosine(in) + H(+)(in)
label_lc: cytosine(out) + h(+)(out) => cytosine(in) + h(+)(in)