I’m running the codes of Setting UI sample and see below code for elm_layout_theme_set.

static Evas_Object*
gl_content_get_cb(void *data, Evas_Object *obj, const char *part)
{
 item_data_s *id = data;
 const Elm_Genlist_Item_Class *itc = elm_genlist_item_item_class_get(id->item);
 Evas_Object *content = NULL;

 if (itc->item_style && !strcmp(itc->item_style, "1line")) {
  if (part && !strcmp(part, "elm.icon.1")) {
   content = elm_layout_add(obj);
   elm_layout_theme_set(content, "layout", "list/B/type.3", "default");
   Evas_Object *icon = create_icon(content, id->index);
   elm_layout_content_set(content, "elm.swallow.content", icon);
  }
 }

 return content;
}

The definition for this function is,

EAPI Eina_Bool elm_layout_theme_set(Evas_Object *obj, const char *clas, const char *group, const char *style);

I cannot find the definition for what values can be set for the group parameter. Anyone knows it? What “list/B/type.3” means?