The Difference Area

The difference area defines the part of the page used to determine if a page has changed. This is only relevant if you are using looseleaf with output differencing.

The difference area is displayed when the Difference tab is selected on the page details. It appears as a green checked rectangle overlaying the other blocks on the page. Any material that lies within this rectangle is treated as significant when comparing pages from two releases for differences.

Make sure the difference area you have defined excludes fixed blocks that display release-specific material, such as release numbers or dates. Including such material in the difference area may lead to false change indications.

To define the difference area, select on of the following options:

Use data area

Make the difference area the same as the data area. This means that all material in data, side note and margin rule blocks will be compared for differences. This is the default.

Cover data blocks

Make the difference area the smallest rectangle that covers the data blocks only.

Cover data and side notes

Make the difference area the smallest rectangle that covers the data and side note blocks only.


This option allows you to set the size of the difference area manually as described in “Changing Block Dimensions”. It is currently not possible to define the difference area separately for left and right pages. Note that the only way to select the difference area is by selecting the Difference tab (you can’t select it by clicking on the page preview).

The Mirror margins checkbox allows you to modify how the position of the difference area is specified. It is only enabled if the Custom option is selected and the page type has different layouts for left and right pages (Double sided is selected) and there is no page mirroring selected. If the page orientation is Portrait, mirroring is done for the left and right margins; if it is Landscape it is done for the top and bottom margins. For more information, see “Block Mirroring”.

Specific content can be ignored during page comparison, even if it lies in the difference area. See the looseleaf section in the User Guide for details.