Thanks for the heads-up. A Google search of "Bangladesh Standard Time site:bd" from UCLA yielded the following examples: BST http://www.parliament.gov.bd/cpa/Time%20Zone.htm http://www.undp.org.bd/info/contact.html http://www.bpdb.gov.bd/download/Meghnaghat%20PQ%20Amendment%20Notice%2018.03... http://www.newstoday.com.bd/index.php?option=details&news_id=2333656&date=20... http://www.lgd.gov.bd/Tenders/PQ_Document.pdf http://www.powercell.gov.bd/index.php?page_id=250 BDST http://mail.banglanews24.com.bd/English/detailsnews.php?nssl=64b69edbdbebddf...
From this admittedly limited sample, it would appear that the most common abbreviation is "BST", with "BDST" being used by banglanews24 but being rare elsewhere.
Perhaps the TZ database should switch to "BST"?