A Catholic high school has enraged hundreds of teenage girls by banning some types of dress from its prom, and demanding students send in pictures of their outfit for approval. Delone Catholic High School, a $5,000-a-year school in McSherrystown, Pennsylvania, started making the demands of its students this year. Authorities have declared war on short hems, cleavage, bare midriffs and nude-colored linings ahead of the May 1 prom. Banned: The above two dresses both violate the rules of Delone Catholic High School. The right-hand dress was deemed acceptable when a 'modesty piece' was added . Delone Catholic High School, a $5,000-a-year school in McSherrystown, Pennsylvania . Some girls say the guidelines were sprung on them by surprise, and have been forced to alter their gowns, or, worse still, been left with inappropriate garments that they can't take back, according to local station Fox 43. Simone Hostetter, who owns a local dress shop, told the channel that parents were being driven to despair by the policy, which could leave them more than $300 out of pocket. She said: 'They’re frantic, more so the parents have been really frantic, calling me with, "Please, please please would you exchange her dress it’s not allowed."' Naked controversy: 'Nude' linings, such as those on the dresses above, were deemed unacceptable at the school, and banned . Hostetter has changed her policy to allow returns in this case - and has started published pictures of her dresses on Facebook, spelling out which ones pass the school's modesty test, and which do not. The school insists the sartorial censorship is vital to preserving 'Catholic values and moral integrity' at the school. In a statement it said guidelines were spelled out in September, and the 'only change' from previous years is a requirement for girls to send in pictures for advance approval. They said the move was a preferable alternative to turning students away at the door. Allowed: These two dresses did pass the test of prom censors at the school. Students and parents are petitioning for the new rules to be dropped . Students and parents have expressed their outrage online, starting a Change.org petition aimed at swaying the principal. It calls the new standards 'antiquated and unreasonable', and complains that the prom is so soon that they have no time to act on the rule change. Writing underneath, student Cheyenne Altland said: 'I feel that my fashion choices for prom do not have any bearing on the strength of my Catholic Faith and my school can not tell me otherwise.'
Students at Delone Catholic High School were hit by new regime . $5,000-a-year school in McSherrystown, Pennsylvania, made the change . Nude linings, cleavage and midriff are banned to preserve 'moral integrity'
Girls must submit photographs to school censors in advance . Parents complain they've been left with un-returnable, expensive dresses . School insists the rules were explained and agreed to in September .