The gn parameter is used to distinguish between multiple instances of a Report Category and retain its attributes (for example, width, height, and refresh rate).
For example, if you add three Report Categories, specify a unique gn value for each instance of that Report Category during the configuration process. The following diagram illustrates this functionality using three WebFOCUS reports:
The attributes you specify for each instance of the Report Category are retained. If all three Report Categories had the same gn value and you changed the width or height of one Category, then the remaining instances would reflect your change and the end result may be unsatisfactory. For more information on configuring Categories, see Adding WebFOCUS Categories to the TIBCO PortalBuilder.