What is actually transmitted in the RF Initializer in XBee Pro initialization for data transmission

XBee & XBee Gateway
,
1

For transmitting a signal, RF Packet is sent that contains RF Initializer as given in the manual under RF Module of operation. It states as under:
An RF initializer is sent each time a new connection sequence begins. The RF initializer contains
channel information that notifies receiving modems of information such as the hopping pattern
used by the transmitting modem. The first transmission always sends an RF initializer.

Question:

  1. What are the actual contents of RF initializer.
  2. How is the hopping pattern used (set by ATHP command - values from 0-6) by the transmitter and the receiver? If it is set to a value of 4 - how is this value used by the radio?
  3. How is this number related to channel selected for communications?
    Thanks