Baju Melayu and Occassions

A black Baju Melayu with a black kain samping embroidered with gold thread is considered a form of formal dress, and is the official attire required during official national events, especially highly formal ones like the official celebration of the Yang di-Pertuan Agong's birthday. Malaysian ambassadors presenting their credentials to foreign heads of state are also required to wear the black Baju Melayu. The white Baju Melayu is worn by Malaysian royalty when mourning the passing away of a member of the royal family.

Malaysian men usually wear the shirt for general religious occasions, such as visiting the mosque or for a religious gathering. Some companies allow their male workers to wear Baju Melayu on Fridays, whereas others have it as a policy. On the whole Singaporeans frequently refer to it as a Baju Kurung, although this term in Malaysia usually refers only to the corresponding outfit for women.

In Indonesia, both the Baju Melayu in both collar styles (and other Malay clothes such as Baju Kurung) is popular in provinces with large Malay populations such as Riau, the Riau Islands, West Kalimantan and a few other provinces. 


Sources:
http://en.wikipedia.org/wiki/Baju_Melayu