The Intel Binary Compatibility Standard (iBCS) is a standardized application binary interface (ABI) for Unix operating systems on Intel-386-compatible computers, published by AT&T, Intel and SCO in 1988, and updated in 1990.
It extends source-level standards such as POSIX and XPG3[1] by standardizing various operating system interfaces, including the filesystem hierarchy layout (i.e., the locations of system files and installed programs),[2][3] so that Unix programs would run on the various vendor-specific Unix implementations for Intel hardware (such as Xenix, SCO Unix and System V implementations).
[4] The second edition, announced in 1990, added an interface specification for VGA graphics.
[5] iBCS, edition 2, was supported by various Unix versions, such as UnixWare and third-party implementations.
1994, enabling Linux to run commercial Unix applications such as WordPerfect.