Many business firms have  casual days  for office attire.
( ( Many ( business firms ) ) ( ( have ( ( casual days ) ( for ( office attire ) ) ) ) . ) )
(ROOT (S (NP (JJ Many) (NN business) (NNS firms)) (VP (VBP have) (NP (NP (JJ casual) (NNS days)) (PP (IN for) (NP (NN office) (NN attire))))) (. .)))
No business firm has ever allowed a casual day for office attire.
( ( No ( business firm ) ) ( ( ( has ever ) ( allowed ( ( a ( casual day ) ) ( for ( office attire ) ) ) ) ) . ) )
(ROOT (S (NP (DT No) (NN business) (NN firm)) (VP (VBZ has) (ADVP (RB ever)) (VP (VBN allowed) (NP (NP (DT a) (JJ casual) (NN day)) (PP (IN for) (NP (NN office) (NN attire)))))) (. .)))