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

Verbs and MDO Variable Access

Working With Mapping Services

10–28 106160 Tandem Computers Incorporated

Verbs and MDO

Variable Access

Verbs manipulate data using variables. When a verb accesses data in a variable, it uses

keywords that support variable access—the ARGS, VARS, RANGE, GENERIC,

BYNAME, MERGE, OVERLAY, DATA, MDO, and MAP keywords. MDO data is

stored in MDO variables. You use the MDO and MAP keywords in verbs to access

MDO variables and maps.

Note Refer to the discussion on verb syntax and variable access methods in the NonStop NET/MASTER NCL

Reference Manual for information on verb keywords that are used to access variables other than MDO

variables—the ARGS, VARS, RANGE, GENERIC, BYNAME, MERGE, OVERLAY, and DATA keywords.

The MDO Operand

The MDO operand is used by verbs to explicitly name the stem of an MDO variable.

The syntax of the MDO operand is:

MDO=

stem-name

specifies the name of any user-defined stem variable that you want to contain

MDO data.

When you name the stem variable, you can give it any valid stem variable name on the

first occasion you use it (normally in the ASSIGN verb when you create the MDO

variable). When you refer to the stem variable on subsequent occasions, NCL

understands that it is an MDO variable and that it must use Mapping Services to

interpret the data. Referring only to the stem of an MDO variable refers to the data

contained in all elements that begin with the stem.

The syntax description shows that MDO variables look like stem variables. You can

think of MDO variables as stem variables from the point of view of variable

substitution. However, the structure of the data contained in an MDO variable means

that the data must be interpreted by Mapping Services.

With one exception, you must always follow the MDO operand with a stem variable

specification. The exception is after the MDO operand on the ASSIGN verb where, in

one syntax format, you can follow the MDO operand with a compound variable

specification. The ASSIGN verb is discussed later in this section.

MDO variables have certain restrictions. An MDO variable cannot be a global

variable. Its scope is restricted to the NCL process that creates it. However, it can be

shared to called procedures or functions in a share list.