class aux_verbs 
{
    <: _aux_verbs;
    desc.ht = value([arg0:@emptyarg_fs,arg1:@emptyarg_fs,arg2:@emptyarg_fs]);
    node Anchor : [cat:aux,id:aux];
    node(Foot).top.mode = value(participle);
    node(Anchor).bot.form_aux = node(Foot).top.aux_req;
    node(Infl).bot.aux_req = value(avoir);
    %% only one advneg may adjoin on the right of aux
    node(Anchor).adjright = value(atmostone);
}