Defining Application-Independent Variables

General syntax of DEFINE DATA INDEPENDENT:

DEFINE DATA

INDEPENDENT [aiv-data-definition ...]

END-DEFINE

This document covers the following topics:

Function
Syntax Description

For explanations of the symbols used in the syntax diagrams, see Syntax Symbols.

Function

The DEFINE DATA INDEPENDENT statement is used to define application-independent variables (AIVs).

An application-independent variable is referenced by its name, and its content is shared by all Natural objects executed within one application that refer to that name. The variable is allocated by the first executed Natural object that references this variable and is deallocated by the LOGON command or a RELEASE VARIABLES statement.

The optional INIT clause is evaluated in each executed Natural object that contains this clause (not only in the Natural object that allocates the variable).

Note:
In an RPC server, application-independent variables (AIVs) are not deallocated implicitly, but stay active across RPC requests, because different clients may have access to the same variables on the RPC server. This means they must be deallocated explicitly using the RELEASE VARIABLES statement. See Application-Independent Variables in the Natural RPC (Remote Procedure Call) documentation.

Syntax Description

Syntax Element	Description
`aiv-data-definition`	AIV Data Definition: The `DEFINE DATA INDEPENDENT` statement can be used to define a single or multiple application-independent variables (AIVs). For each AIV, the syntax shown in AIV Data Definition applies.
`END-DEFINE`	End of DEFINE DATA Statement: The Natural reserved word `END-DEFINE` must be used to end the `DEFINE DATA` statement.

AIV Data Definition

`level`		`variable-definition`
		`redefinition`

Syntax Element Description:

Syntax Element Description

Syntax Element	Description
`level`	Level Number: An application-independent variable must be defined at Level 01. Other levels are only used in a redefinition.
`variable-definition`	Variable Definition A `variable definition` is used to define a single field/variable that may be single-valued (scalar) or multi-valued (array). For further information, see Variable Definition. Note: The name of an application-independent variable must start with a plus (+) character.
`redefinition`	Redefinition: With a `redefinition`, you can partition an application-independent variable into one or more subfields. For further information, see Redefinition. The subfields resulting from the redefinition must not be application-independent variables; that is, their name must not start with a plus sign (+). These fields are treated as local variables.

level

Level Number:

An application-independent variable must be defined at Level 01. Other levels are only used in a redefinition.

variable-definition

Variable Definition

A variable definition is used to define a single field/variable that may be single-valued (scalar) or multi-valued (array).

For further information, see Variable Definition.

Note:
The name of an application-independent variable must start with a plus (+) character.

redefinition

Redefinition:

With a redefinition, you can partition an application-independent variable into one or more subfields.

For further information, see Redefinition.

The subfields resulting from the redefinition must not be application-independent variables; that is, their name must not start with a plus sign (+). These fields are treated as local variables.

Note:
The first character of the name must be a plus (+). Rules for Natural variable names apply, see Naming Conventions for User-Defined Variables in Using Natural Studio.