Dhaka University (DU) will observe August 23 as the “েBlack Day”ে in memory of the “েinhuman, sad and condemnable” attack on the university’s teachers, students and officials on August 20-23, 2007.To mark the day, teachers, students, officials and employees of the university will wear black badges, said a DU press release here today.A discussion will also be held at the Teacher-Student Centre (TSC) around 11:30 am with DU Vice-Chancellor Professor AAMS Arefin Siddique in the chair, added the release.On August 20, 2007 army personnel assaulted three students and insulted a teacher of DU at gymnasium playground during a football match, triggering clashes between police and students at DU and other educational institutions across the country.A number of teachers and students of different universities, including Rajshahi and Dhaka Universities, were arrested following the clashes on charges of violating emergency power rules.