class adv_before_v {
     %% Adverbs on verbs
     %%      may occur before non tensed verb
     <: adv_modifier;
     node Root : [cat: v];
     Anchor < Foot;
     node(Foot).top.mode = value(infinitive|participle|gerundive);
     %% no argument in this case
     desc.@kind0 = value(-);
     %% accept 'très chantant'
     Adv +
         node(Adv).bot.adv_kind = value(~très)
         |
         node(Foot).bot.mode = value(gerundive|participle)
         ;
}