An enhancement and preprocessor to native file tailoring functions such as ISPF's File Tailor utilities. A set of control parameters and input data is processed according to specified options to prepare one or more tables of data compatible with the native file tailoring functions, and the native file tailoring functions are called one or more times to achieve the desired tailored files. Use of the invention obviates the need for custom programming or manual file editing to format source data into one or more tables which are compatible with the input requirements of the native file tailoring functions.