Shared variables

Shared variables are an optional-facility. They are defined as an interface between cooperating APL sessions. They may be used to provide an interface between APL programs and non-APL system facilities.A variable can be shared by precisely two sessions; these are called the partners in the sharing. The partners can be either APL sessions or auxiliary-processors. An auxiliary-processor is a program, possibly written in a programming language other than APL, that communicates with an APL program through shared-variables.Auxiliary-processors are used to extend the semantics of APL without adding new entries to the form-table. They can be used to permit a conforming-program to access services not available in the standard APL environment through sequences of assignments and references to shared-variables. Conforming-programs that use shared-variables should document this fact, since shared-variables are not a defined-facility of this standard.