The ITU (International Telecommunication Union) produce a classification system for each type of radio wave, describing in 3 characters how a radio wave is modulated. Modulation is the act of putting information onto a radio wave, and includes pulse modulation, frequency modulation or amplitude modulation. The first letter is how the wave is modulated, the second character is what type of information is modulated onto the wave (digital, analogue, etc.) and the third is the information output (morse code, voice, etc.).

The 3 character abbreviation for an old style NDB ident is A1A (These have keyed morse code modulation, BFO mode must be used to here the ident.), and a newer NDB ident is A2A (which has amplitude modulated morse code, so you can listen to it in any mode). The NDB carrier wave is N0N; it is not modulated and carries no information.

The learning objectives also state that we must know the classification for VHF communication waves, which is A3E as per the above LO.

This is the limit of the learning objectives on these classifications. You do not need to find and memorise the table.