ccs bootloader question

[wirelessage]

Hello all:

I am just starting work on bootloader. I came across the CCS Bootloader on CCS website.

I was also looking at the loader.c file in the examples code which loads the program. I observe that it:
a) receives 64 bytes at a time and writes to program memory.
b) does checksum verification.

My questions are:
a) What is this line of code do in loader.c file?
if (do_ACKLOD)
putchar (ACKLOD);

putchar(XON);

Seems like putchar(ACKLOAD) requests the client to send next payload if checksum passes, else it just sends a putchar(XON) and the client is smart enough to re-send the data????

b) If what I am assuming is true, and the example software takes care of re-transmission, then I don't have to worry about retransmission/checksum issues right? If I am not reading this correctly, please advise...

Thanks!
WirelessAge.