Shared Variables
Shared Variables are a feature of the programming language APL which allows APL programs running on mainframe computers to communicate with other facilities on a computer, which can include external files, database management systems (DBMS), or other users. Shared Variables were first introduced by International Business Machines Corporation (IBM) in their APL.SV software product in 1973, and are still available as of 2015, in APLs from IBM and Dyalog, for the operating systems Linux and Windows.