Hierarchical File System (IBM MVS)
POSIX-STYLE FILE SYSTEM FOR IBM'S Z/OS AND ITS PREDECESSOR OPERATING SYSTEMS FOR Z SYSTEM MAINFRAMES
IBM HFS; Z/OS HFS; Z/OS Hierarchical File System; HFS (IBM); Hierarchical File System (IBM); Hierarchical file system (IBM MVS)
IBM's Hierarchical File System (HFS) is a POSIX-style file system that IBM introduced on Feb 9, 1993 in MVS/ESA System Product Version 4 Release 3 OpenEdition