Students and alumni are also voicing concerns.

In order to attend prom, each girl at Delone Catholic High School in McSherrystown, Pennsylvania, must send in photos of the front and back of her dress for approval.

Shane Dunlap / Via Twitter: @shanedunlap

"Women's gowns may not be extremely short, have an extremely low cut front or back, have any excessively high cut slits, have overly revealing midriffs, or be inappropriately revealing — giving the illusion of nudity," the guidelines state.

Flickr: povertybarn

"Our children will not undergo scrutiny of prom gowns based on outdated, unrealistic expectations and rules implemented at such short notice," a Change.org petition states.

Nickie Russell, a mother who signed the petition, told BuzzFeed News the school has rejected both of her daughters' dresses. Russell bought them for a combined $988 months before the school emailed her about the rule, she said.

"It's frustrating," Russell said. "I am a rule person and if you saw my daughter's dress, it has only two very small panels of sheer on the side, but it's a nude color dress. I bought it for her. As a mom, I thought it looked fine."

The school told her the sheer part of her daughter's dress was an allusion to nudity.

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