This palette can only be used in Extended mode.
This palette is used to assign pages to more imposition types. The only two active controls on this palette are Automatic page assignment and Set number of sheets. Other features serve informational and navigational use only (e.g. switching to the previous and following imposition).
If Automatic page assignment is enabled it affects all pages on the Pages for imposition palette, not just pages for the active imposition - pages are divided into impositions automatically and controlled by this palette, specifically by the setting of the maximal number of sheets.
Example: The cover of a brochure can be imposed separately in the first imposition, the next imposition can contain the inside of the brochure which will be processed by 'cross-fold' and the last imposition can contain the rest of the brochure processed by 'work and turn'. This can be done by selecting 'Booklet' (or loading it from a template including its parameters) and limiting number of sheets to 1. Then, in the second imposition, 'cross fold' is selected. If the sheet is filled as desired (depending on the amount of pages for imposition) you are done. If, however, there are still too many empty positions and you want to impose some of the pages on a smaller sheet or for 'work and turn' you need to limit the amount of sheets for this imposition (usually lower by one than it is without limits) and add another imposition, where you select the imposition you desire (e.g. 'work and turn') and you are finished.
The same result can be obtained by disabling automatic page assignment and manually assigning pages to individual positions (first and last page to the first imposition, inside on the second imposition and the rest on the third imposition). This method is, however, more time-consuming and prone to make mistakes - especially while determining which pages will be placed on the last imposition ('work and turn') because it is really easy to make a mistake in that.