There is only one file type that uses the .NBC extension:
Next Byte Codes Source Code File
File written in Next Byte Codes (NBC), a programming language used to program LEGO NXT programmable bricks; contains source code with an assembly language-like syntax and can specify instructions for brick motion; used for programming movements for LEGO robot parts.
NBC files can be compiled with the NBC compiler (called "NBC"), or with Bricx Command Center (BricxCC), a Windows IDE that includes the NBC compiler.
Updated: May 23, 2011