# System Parameters

'+N' | Allow NULL Perform Value

## Description

The '+N' parameter controls whether the PERFORM directive will generate an error when an empty/null string is passed to a PERFORM directive.

By default, this parameter is On, which indicates that a NULL string is accepted.

When Off, a NULL string would be considered an error. (Pre-Version 7.10 PxPlus functionality)

When the PERFORM directive encounters a NULL string (and '+N' is On), the directive does not generate an error and simply proceeds to the next directive. In other words, the PERFORM does nothing.

(The '+N' system parameter was added in PxPlus v7.10, build 9170.)

## Default

On

## See Also

PERFORM Call Subprogram, Share Variables