Mumbai, March 18 -- The initial public offering (IPO) of Embassy Office Parks REIT, India's first real estate investment trust, witnessed 20% subscription on the first day, according to stock exchange data. The Embassy REIT, backed by private equity firm Blackstone Group LP and Bengaluru-based developer Embassy Property Developments Pvt. Ltd, aims to raise Rs.4,750 crore through the IPO with units issued in a price band ofRs 299-300 apiece....