The nonstandard stuff could not be found in in the first pubslished versions of the program. The first version I am aware of, is a program called 0125725 SUGtar published at the Sun User Group meeting in december 1987, a different publishing of the same ustar00which has been originally written by John Gilmore was called PDtar. In 1987 PDtar/SUGtar was implementing a true subset of the 1987 POSIX-1003 draft (missing only the long name splitting). FSF people then later added t_atime... making GNU tar non POSIX compliant. When FSF added the sparse file handling stuff, this was done in a way that even violates any tar document available since the late 1970's. GNU tar is not tar...