FAA: see point 2/d/
[URL="http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0502.html"]
5-2-2. Pre-departure Clearance Procedures
a. Many airports in the National Airspace System are equipped with the Tower Data Link System (TDLS) that includes the Pre-departure Clearance (PDC) function. The PDC function automates the Clearance Delivery operations in the ATCT for participating users. The PDC function displays IFR clearances from the ARTCC to the ATCT. The Clearance Delivery controller in the ATCT can append local departure information and transmit the clearance via data link to participating airline/service provider computers. The airline/service provider will then deliver the clearance via the Aircraft Communications Addressing and Reporting System (ACARS) or a similar data link system or, for nondata link equipped aircraft, via a printer located at the departure gate. PDC reduces frequency congestion, controller workload and is intended to mitigate delivery/readback errors. Also, information from participating users indicates a reduction in pilot workload.
b. PDC is available only to participating aircraft that have subscribed to the service through an approved service provider.
c. Due to technical reasons, the following limitations currently exist in the PDC program:
1. Aircraft filing multiple flight plans are limited to one PDC clearance per departure airport within a 24-hour period. Additional clearances will be delivered verbally.
2. If the clearance is revised or modified prior to delivery, it will be rejected from PDC and the clearance will need to be delivered verbally.
d. No acknowledgment of receipt or readback is required for a PDC.
e. In all situations, the pilot is encouraged to contact clearance delivery if a question or concern exists regarding an automated clearance.
Then Australian:
ENR 1.1-5 paras 3.24 - 3.24.8 detail
PDC READBACK
After you get your PDC via ACARS the pilot is free to contact DEL (if it exists) or GND (if it doesn't) when ready to do so. The aircraft must read back the SID (and assigned transition if there is one), assigned runway, STAR (if given), any conditional requirements, squawk, and current parking stand. If done on GND it must be done prior to requesting push or taxi.
QF1 => Sydney Clearance Delivery, QF1, PDC Readback
DEL => QF1, Sydney Delivery
QF1=> DEL, RWY 34L RICHMOND2 DEP, RIC trans, 3324, Bay 31
DEL => QF1
The readback of the call sign by ATC is acknowledgement that the readback of the PDC is correct, this is all the pilot needs to be able to proceed. In the above example the aircraft could now call GND and ask for further clearances as per normal, there is no need to be told to call GND, you just do it. Note that assigned altitude is not one of the things that has to be read back.