class sep_sentence_punct_coma
{
    <: sep_sentence_punct;
    node(Punct).lex = value(',');
    node(S2).top.extraction = value(-|wh);
    node(Foot).bot.mode = value(~-); % avoid application on short sentences
    S2 +
        node(S2).top.extraction = node(S).top.extraction
        |
        node(S2).top.extraction = value(-)
        ;
}