Here’s the e-mail from Juergen Zeller that started it all:
Date: Fri, 14 July 1995 12:29:49 +0200
Reference: Endings for Layer3: mp3
Hello,_according to the overwhelming opinion of all asking: the ending for ISO MPEG audio Layer 3 is mp3.
i.e. we should for coming www sides, Shareware,_Demos, etc. on it respect that no more bit endings rausgehen.
It has a reason, believes me : -)