IBM virtual storage operating systems added VSAM, which supports indexed files as Key Sequenced Data Sets (KSDS), with more options.
Support for indexed files is built into COBOL[1] and PL/I.
[2] Other languages with more limited I/O facilities such as C support indexed files through add-on packages in a runtime library such as C-ISAM.
[3] Some of Digital's operating systems, such as OpenVMS, support indexed file I/O using the Record Management Services.
In recent systems, relational databases are often used in place of indexed files.