What is readback_p1 and readback_p2 on avrdude configuration

Development Boards MicroMod
1

Hi there,

I am trying to add support for ATmega8U2 for avrdude, and for that I have to write configuration file for ATmega8U2, but I dont understand that what is readback_p1 and readback_p2 in configuration file? As it is given for other devices in the file. I found it from edaboard discussion that it is hardware ID, But what is this ID and where I can find it in datasheet of the ATmega8U2 ? and Why it is different for EEPROM and FLASH ???

Any help will be greatly appreciated .

Thanks,

Chris