Vertical space retention

The Space above and Space below groups allow you to control whether vertical space is discarded or retained.

By default, inter-paragraph space is discarded at the top and bottom of page or when the page type changes. There are times however when retaining this space is desirable.

For example, consider a page width table followed by double column text. Normally we would like to generate a small vertical space to avoid the text crowding the bottom of the table. A standard Below space however will be discarded because of the change in page type from single to double column. To ensure that the space appears select Retain at internal boundaries in the Space below group.

Note that doing the same for Space above the two column text would not have the same effect, as the space would appear above the first column only.

The Retain always option is similar, except here the space is always generated, even at the top or bottom of a page. You would use this option to insert a fixed space above a heading.

There is a significant difference in the behavior of a sequence of vertical spaces, in that soft vertical spaces overlap while retained spaces accumulate. To calculate the total vertical space allocated, use the following formula:

  • at a page boundary, allocate the sum of all Retain always spaces in the sequence;

  • at a page type (internal) boundary, allocate the sum of all Retain … spaces in the sequence (this value is known as the total retained space);

  • otherwise allocate the larger of the total retained space and the largest discardable space in the sequence.

[Note] Note

At a forced page break or page type change, any pending retained vertical space is allocated immediately and retained space is discarded.