NET/MASTER Network Control Language (NCL) Programmer's Guide

Language Features
NCL Summary
106160 Tandem Computers Incorporated 2–5
You can use these language constructs to design, debug, and integrate NCL
procedures in a structured way. You can design a small module of code and debug it
by using the DEBUG commands. In addition, you can progressively integrate
modules that are known to be error-free.
The DEBUG commands are discussed in detail in Section 9, “Debugging an NCL
Process.”
Scope Everything that NCL does, it does within boundaries. These boundaries limit what a
procedure, function, or language construct can do. These boundaries define the scope
of NCL activities and its language constructs.
Scope and Environments
An important aspect of scope is the concept of environments. An environment is an
area in which NonStop NET/MASTER MS users, NonStop NET/MASTER MS
commands, and NCL processes operate. The concept of an environment is designed to
limit the scope of the default activities of NonStop NET/MASTER MS commands and
NCL processes.
NonStop NET/MASTER MS environments are discussed in detail in Section 16,
“Environments and Command Processing.”
Scope and Core Statements
Scope affects some core statements. Two core statements, for example, that are
affected by the concept of scope are the PROCEDURE and FUNCTION statements.
The activities of a procedure are bound by its initial PROCEDURE statement and its
terminating END statement. The activities of a function are bound by its initial
FUNCTION statement and its terminating END statement. Other core statements that
are affected are DO, GOTO, GOSUB, IF, SELECT, and SIGNAL.
For more on these core statements, see Section 5, “Controlling Execution Flow,” and
Section 6, “Procedures and Functions.”
Scope and Verbs
Scope affects some verbs, such as the family of VARTABLE verbs. When you create a
new vartable using VARTABLE ALLOC, for example, you can explicitly specify its
scope, using certain keywords: whether the vartable is local to the NCL process that
creates it (PROCESS), whether it is available to all NCL processes executing in the
same region (REGION), or whether it is available to all NCL processes executing in the
same NonStop NET/MASTER MS system (GLOBAL).
Regions are discussed in Section 16, “Environments and Command Processing.”
Scope and Labels
Scope affects labels. It affects the visibility of labels within a procedure and function
and affects the scope of label searching. It also affects the labels to which a core
statement such as DO, GOTO, GOSUB, and SIGNAL LABEL can jump.