class verb_mod_extraction_wh
{
    <: verb_mod_extraction;
    <: wh_sentence;
    node(S2).top.extraction = value(wh);
    node(S2).top.xarg.case = value(-);
    node(XGroup).extracted.real = value(PP|pri);
    node XGroup: [type: alternative];
    %% Realization of other args as a wh pronoun
    node pri_arg : [cat:pri,id:pri,type:coanchor,bot: [case: ~nom|acc|comp]];
    XGroup >> pri_arg;
    - pri_arg::agreement; pri_arg = pri_arg::N;
    %% Realization as wh-PP
    node PP : [cat:PP,id:wh,type:subst,top: [wh:+,real:pri|N2]];
    XGroup >> PP;
    pri_arg < PP;
    %% WARNING: should add case for XGroup filled by
    %% locative, temporale, manner pri (où, quand, comment)
    %% but we need some marker on these pronouns
}