Several important notes about this table:

ROGER vs. WILCO: This is one of the most common errors made by pilots. ROGER means you heard the transmission and understand it. WILCO means you understand the instruction AND you will execute it. If ATC gives you a heading, altitude, or speed instruction, you respond with WILCO. If ATC gives you information (weather, traffic, etc.), you respond with ROGER to confirm you received it.

Example contrast:

GO AHEAD is deprecated. ICAO documentation recommends discontinuing the use of GO AHEAD. In modern standard phraseology, ATC simply keys the microphone or waits for you to make your transmission; explicit permission is no longer required. However, you will still hear it in practice, particularly from older controllers or in certain regions, so you must understand it when you hear it. Do not be surprised if you encounter it during training. For your radiotelephony practice, preferably avoid transmitting it; listen for it but do not initiate its use.

ACKNOWLEDGE vs. ROGER: Some textbooks mention ACKNOWLEDGE as a separate procedure word. ACKNOWLEDGE is primarily used by ATC to request that you confirm receipt ("Acknowledge this clearance by readback"). As a pilot, you acknowledge by reading back the critical parts of the clearance. ACKNOWLEDGE as a standalone word is ATC phraseology; you respond with your readback.