From the Norton Guides: F: is used in combination with the value specified with the FILES command in CONFIG.SYS to inform CA-Clipper of the maximum number of file handles to use. This setting is only valid for application programs using more than 20 files and running under DOS 3.3 or greater. When specified, CA-Clipper determines the number of files that can be opened using the smaller of the F setting and the CONFIG.SYS FILES value. For example, if the FILES command is set to 120 and the F parameter is set to 50, the maximum number of files that can be opened is 50. The ideal is an odd number and 5 less than specified with the FILES command.