Is not right to have specific-gender "dress code" in graduation!

At Jacksonville High School in the state of Texas a student received a letter from the school stating that females are only allowed to wear skirts or dresses, and males are only allowed to wear slax, shirts, and a tie to graduation. Do you think that the school policy violated the IX article according to the policy of specific-gender "dress code" for graduation? The student believes that she is being discriminated according to her sexual preference.