Shoutcast log file player type?

[packzap]

In ye old Shoutcast log there comes an entry when a person logeth on to me stream. Here by example:[dest: 1.2.3.4] starting stream (UID: 2468)[L: 12]{A: WinampMPEG/2.7}.

But, yo, sometimes it says something like the above, but behold, the last bracket shows this: {A: }. No player entry is shown.

Here cometh the questions. What does the "A" stand for? And more importantly, what could it possibly mean when the player information is vacant? What, how, and where are the player names deciphered by the beloved SHoutcast server?

I humbly await any thoughtful responses and say thanks in advance.