CBL, COBOL Source Code File (.cbl)
The CBL Developer file format
CBL files contain source code written in the Common Business-Oriented Language (or short: COBOL). COBOL is, albeit old, still in use nowadays. COBOL and it's according CBL files are most often used when developing software for business use, as well as for accounting and administration. CBL files have to be compiled before they can be executed or run by a system. This can be achieved using a COBOL compiler.
Technical details of CBL files
CBL files contain source code in a plain text format. However, in order to open and view them in a text editor, the appropriate support for the specific file standard is needed. COBOL versions in use include, COBOL-68, COBOL 2002 and more.