byte addr elements question

I'm studding one wire library to work with one wire ds18b20 sensor and looking to the examples I found this that is bugging me what this code is doing

define MAX_DS1820_SENSORS 2

byte addr[MAX_DS1820_SENSORS][8];

I can't understand what will be happen on this line Is this a multi array element?

This is a two dimensional array. The address of a one wire sensor is 8 bytes long and here 2 sensors are used, so room for 2 times 8 bytes.

ok so addr[1] will contain the address of first sensor with 8 bytes long and addr[2] will contain the address of the second sensor, is this correct?

No, the indexes start counting at 0, not 1. The first one is addr[0], the second one is addr[1].

yes my mistake i forgot 0:( Thanks for help