nrf24l01 Network header type help

Hello,

I am using the 2014-2015 - Optimized RF24 Network Layer for NRF24L01 radios along with the TMRh20 2014 - Optimized Fork of NRF24L01+ Driver libraries to create a network of what is now 5 nodes(including master) but will eventually be 19 nodes in total.

I simply curious about the header types. it says types 0-127 are user defined and 65-127 receive a network ACK and all but i am having trouble finding any documentation as to what this really means. currently I am defining tx headers with:

RF24NetworkHeader header(/slave_address/);

by default does the network.write() with default header type return an ACK from the slave node? or just return true if the message was transmitted?

I need to confirm that node 011 for instance actually received the message.

is the header type defined automatically by the data type that it is sending? if not what are the data types? i have seen a lot of people adding 't' or 'p' or 'b' for header types. what numbers to these correspond to?

thanks in advance for any information you can give.