BEM methodology and sub-blocks

First of all, the BEM methodology process has the premise: blocks is a set of elements, however elements can see blocks, and of course, both can have modifications.

See its structure:

nav.c-ngroup

  //-div e bloco class modificador 
modificador

  div.wrap

    //- bloco

    .row

      //- col bloco md-2 modificador

      .col-md-2

        //- elemento

        h4.c-ngroup__title Promote

        //- bloco 

        ul.c-ngroup__list

          // elemento/ bloco

          li.c-ngroup__list__item

            //- elemento semântico 

            a(href='#') Event
         ...

CSS / less

.c-ngroup__list{
   &__title{
   }
   &__item{
     a{

     }
   }
}

Yes, nesting two levels of elements is a bad practice in WELL. The correct one, according to the methodology , is to ignore intermediate levels when naming element classes.

Class c-ngroup__list__item would be c-ngroup__item and class c-ngroup__list__link would be c-ngroup__link .