Contactless Clamshell Card

Hi all,
I am doing a RFID project, I have used HTRC110 Chip for reading the RFID TAG, I wrote the code for reading the TAG, I need to know the data format of Contactless Clamshell Card, i am using 89v51 as my co-processor,... Can anyone tell me what is the start bit and stop bit of the data...