CFEXT

This parameter specifies component file filename extensions.

CFEXT is a string that specifies a colon-separated list of one or more extensions, including any period (".") which separates the extension from its basename.

If undefined, CFEXT defaults to .dcf: on Windows and OS X, and .dcf:.DCF: on all other platforms.

In the Windows case, this means that 'myfile'⎕FTIE 0 will search first for a file named myfile.dcf , and then for a file named myfile (with no extension). As file names are not case-sensitive under Windows, this will find myfile.DCF or MyFile.Dcf and so forth. If none are found with this extension, it will load myfile , MyFile , MYFILE etc.

In the second (non-Windows) case note that 'myfile'⎕FTIE 0 will search first for a file named myfile , then myfile.dcf , then myfile.DCF .