How many buttons required for jukebox?

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How many number and letter buttons are required to make a functional jukebox?  

I have not started looking into software yet, so I am not familiar with how it all gets configured.  I have an opportunity to purchase a front panel of a jukebox which has numberical buttons (0,1,2,3,4,5,6,7,8,9) and (A,B,C,D,E,F,G,H,J,K) buttons.     I was not sure whether arcade software allows you to use letters and numbers together so I was unsure whether I needed letters or whether I should try to find a panel which has more buttons.  

How does arcade jukebox software allow you to map songs to number/letter sequences?  Does it do it for you (including letters and numbers) or must I map each song to a number/letter sequence myself?