There is only one file type that uses the .OB2 extension:
Oberon-2 Source Code File
An OB2 file is a source code file written in the Oberon programming language. The file contains a module that may include definitions, variables, constants, and functions.
Oberon-2 was developed in 1991 from the original Oberon programming language. OB2 modules function as building blocks of Oberon applications that can be compiled into programs using the Modula-2 and Oberon-2 compilers available in XDS.
Updated: May 16, 2016