( ( ( Specification ( of ( ( ( ( ( ( ( ( lens power ) , ) ( base curve ) ) , ) thickness ) , ) and ) ( edge thickness ) ) ) ) ( of ( firm lenses ) ) ) . )
(ROOT (NP (NP (NNP Specification)) (PP (IN of) (NP (NP (NN lens) (NN power)) (, ,) (NP (NN base) (NN curve)) (, ,) (NP (NN thickness)) (, ,) (CC and) (NP (NN edge) (NN thickness)))) (PP (IN of) (NP (NN firm) (NNS lenses))) (. .)))
Specification of lens power, base curve, thickness, and edge thickness of firm lenses.
(ROOT (S (NP (DT A) (JJ concave) (NN lens)) (VP (VBZ is) (NP (NP (JJR thicker)) (PP (IN at) (NP (DT the) (NNS edges)))) (SBAR (IN than) (S (NP (PRP it)) (VP (VBZ is) (PP (IN in) (NP (DT the) (NN middle))))))) (. .)))
A concave lens is thicker at the edges than it is in the middle.