Such requirements could arise either as a result of voluntary agreements among retailers and apparel suppliers or be mandated through regulation.
( ( Such requirements ) ( ( could ( ( ( ( arise either ) ( as ( ( a result ) ( of ( ( voluntary agreements ) ( among ( retailers ( and ( apparel suppliers ) ) ) ) ) ) ) ) ) or ) ( be ( mandated ( through regulation ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Such) (NNS requirements)) (VP (MD could) (VP (VP (VB arise) (ADVP (RB either)) (PP (IN as) (NP (NP (DT a) (NN result)) (PP (IN of) (NP (NP (JJ voluntary) (NNS agreements)) (PP (IN among) (NP (NNS retailers) (CC and) (NN apparel) (NNS suppliers)))))))) (CC or) (VP (VB be) (VP (VBN mandated) (PP (IN through) (NP (NN regulation))))))) (. .)))
voluntary agreements among retailers can bring requirements about the market. 
( ( ( voluntary agreements ) ( among retailers ) ) ( ( can ( ( bring requirements ) ( about ( the market ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ voluntary) (NNS agreements)) (PP (IN among) (NP (NNS retailers)))) (VP (MD can) (VP (VB bring) (NP (NNS requirements)) (PP (IN about) (NP (DT the) (NN market))))) (. .)))