Although Stephen Bourne himself acknowledged that csh was superior to his shell for interactive use, it has never been as popular for scripting. Initially, and through the 1980s, csh could not be guaranteed to be present on all Unix systems, but sh could, which made it a better choice for any scripts that might have to run on other machines. By the mid-1990s, csh was widely available, but the use of csh for scripting faced new criticism by the POSIX committee, which specified that there should only be one preferred shell, the KornShell, for both interactive and scripting purposes. The C shell also faced criticism from others over the C shell's alleged defects in syntax, missing features, and poor implementation.