Using More Than One Page Type on a Page

The mappings have controls that allow you to start a new page and to select a page type on the Start Tag and End Tag tabs. If you change the page type without starting a new page the output page will be formatted using more than one page type. Each part of the page formatted with a particular page type is called a segment, and the page is called a multi-segment page.

Before looking at the technicalities, let’s look at a common reason for using more than one page type on a page — mixing single and double column text:

In the above example, the mapping for the <chapter> tag starts a new page using a page type that produces a single column (in the Start Tag tab). The mapping for the chapter <title> (which, in this case, contains the text “Overview”) switches to a double-column page type in the End Tag tab.

This leads to a page with two segments:

The boundary between segments is important. By default, space before and after a block set in the Paragraph tab is discarded at the boundary between segments (called an internal boundary because it is a boundary within a page). Use the vertical space retention properties of the Paragraph tab to force the space to appear.

Notice in the above example that the header fixed block is in the first segment, while the footer fixed block is in the second. Although you may expect that the header comes from the page type in the first segment and the footer from the second, in fact all fixed blocks are taken from a single page type (by default, the page type used in the last segment). When you mix different page types on a page it is advisable to ensure that they all have fixed blocks in the same places, otherwise there is the possibility that fixed block material will occupy the same space as some of the text. A good way to ensure this is to make sure all page types on a page use the same template.

[Note] Note

You can use the <page-properties/> command to select fixed blocks from the page type in the first segment on the page.

A page break can only appear within a segment if the height of the segment is greater than the current minimum segment height. The can be set for the whole document by using the <topleaf-properties/> command, or for the current segment using the <segment-properties/> command.

It is important to note that selecting a page type has an effect, even if it is the same page type that is currently selected. Selecting a page type always starts a new segment, which can have the following effects:

  • All running heads will be cancelled.

  • Any pending column footnotes and column floats will appear.

  • If there are two or more columns, the columns will be terminated and possibly balanced within the segment. The following diagram shows the effect on the flow of text when the same two column page type is used to make two segments:

[Warning] Warning

Ensure that all page types used on a page have the same paper size and orientation. Failing to do this may lead to unpredictable results.