.ext

A period (.) followed by up to three characters giving the filename extension. You can specify an extension of spaces by putting just the period. If you omit the whole extension, the system supplies one of the following extensions:

.cbl For a source code file
.obj For the output object code file
.lst For the output COBOL source listing
.grp For the output object code listing
.int For the output intermediate code file
.gnt For the output generated code file

Note: You can use the OSEXT Compiler directive to change the default extension for a source code file to something other than .cbl.