Ullman 4.1

Question

What language does this grammar generate?

S-->(L)|a
L-->L,S|S

Comments

it is genrating,

L={a  , (a)  , (a,a)  ,  (a,(a))  ,  ((a),a)  ,  (a,a,a)  ,  ((a),a,a)  ,  (a,(a),a)  , (a,a,(a))  ,  ((a,a),a) ,  (a,(a,a))................}

in naive words, i can say that it is generating all  possible partitioning of a set of all possible length>0 defined on

U={a}

i dont know what actually is an interpretation of above language..