People focused on the characteristic of Kaisho having the Tsukeshoin (a type of window), Chigaidana (a set of staggered shelves), oshiita, the place to decorate with karamono and equipment that would lead to the later Shoinzukuri (architecture of a study room), but it is the adjoining small room that has those items.
会所では、付書院とか違い棚とか押板とか、唐物の飾りの場としての性質、後世の書院造につながる設備が注目されるが、そういったものがあるのは、附属の小部屋である。