The term MP4 RELATIVE is composed of two crossword solutions, AVI and 3 letters. AVI stands for Audio Video Interleave, which is a multimedia container format developed by Microsoft as part of its Video for Windows technology. It is the most common format for audio and video playback, and is supported by almost all media players. The 3 letters refer to the file extension used for AVI files, which is .avi. Therefore, MP4 RELATIVE is a term used to describe a file format related to AVI, such as the MPEG-4 Part 14 (MP4) format.