U3D
From Just Solve the File Format Problem
U3D (Universal 3D) is a standardized format for storing compressed 3D graphical data. It was developed by a consortium of companies including Intel, Adobe, and Boeing, and issued as an ECMA standard (ECMA-363). It is supported for embedding in PDF files.
Identification
U3D files start with bytes 55 33 44, or "U3D" in ASCII.
