The address type, hop count and length fields are put together in the telegram octet following the 'Destination Address' field.
Address Type
Represents 1 bit: D7
See the 'Destination Address' field.
Hop Count
Represents 3 bits: D6, D5 & D4
For more information about the usage of the 'Hop Count' field see here
Length
Represents 4 bits: D3, D2, D1 & D0
The 'Length' field defines the number of extra octets in the 'Payload' field.
Example: length = 3, this means that the payload contains 3 extra octets, see the 'Payload' article.