XBee library for XBee Series 2 modules

In this library what is the packet format is used in sending the data from one XBee module to another XBee module wirelessly ? I want to broadcast data to 3 XBee modules for that I can use ZBTxRequest() function with broadcast address. but i want to know which of the remaining module received this data and which is not received (An acknowledgement from the received modules)..How can i do this?

I'm not sure whether broadcast transmissions return ZigBee Transmit Status frames (type 0x8B) for each receiving device or not. If not, then the application code (assuming something programmable is attached to the receiving XBees) would need to respond. This might be desirable anyway depending on the data integrity requirements. Personally I might avoid broadcasts (see the product manual for a discussion as to why) and send three unicast transmissions. Even then, there is the question whether the Transmit Status frame is sufficient or if a reply from the receiving application is required.