Unlike programs for layout and design, where specific objects (like pictures) are placed in prepared frames, Imposition software places different pages on the same positions of different sheets as needed in a specific situation (for example the second sheet will contain a page different from a page on the same position of the first sheet). Therefore, specific pages are not placed on sheets – a mechanism of assignment is created to place pages on positions. This does not have to be done when using a pre-made template because templates already contain such mechanism.
Pages are placed on positions of the sheet according to a scheme which determines which page from all pages for imposition will be placed to a certain position. This is done by setting a page order in the Pages for imposition palette for a page placed on a certain position. When the first sheet is filled, further sheets are filled automatically following the same scheme.
If the scheme contains a page no. 1 on the position no. 1 and page no. 2 on position no. 2, the second sheet will contain page no. 3 on position no. 1, page 4 on position no. 2 etc.
Page order in the Pages for imposition palette is the main factor for the scheme, not a specific page number – the same imposition will work with different pages or even files with different amount of pages. This is why page order is calculated automatically when dragging a page from the palette or when setting the page number by double-clicking a position and the page order (not a specific page) is then assigned to a position. If a page is then removed from pages for imposition the following page will be placed on this position because it will then have the same page order, as the page that was removed had.
Page order is calculated according to the page's position on the Pages for imposition palette. Pages which are removed from the imposition (unmarked), however, do not affect the order. Pages are numbered from nr.1 just like page order and both these values are equal until one of the pages is unmarked – removed from imposition in which case the page number will increase and page order will remain the same. The order will increase when another page is marked for imposition and since then the number and order differ in value.
Page number (shown in the Pages for imposition palette) and page order will be the same in standard imposition. If, however, for example page no. 2 will be left out of the imposition, the following page – no. 3 will be placed on position no. 2, because it is now second in the order of pages for imposition.
For impositions of the Booklet type the scheme also contains information about the order of order numbering – if it is numbered from the beginning or from the end of the pages for imposition. On the sheet is placed first page and the last page, second and second to last etc. for this type of imposition. In both cases (omitting page from an imposition and numbering from the end) page order is shown in a smaller font and in brackets under the page number in the middle of each position on the work area. The last page will be labeled (Last), second to last (2 from end)... This number will also be shown in the Info palette (and can be changed here) while selecting a position on the work area. When assigning a page to a position by dragging it from the Pages for imposition palette or double-clicking the work area and typing a number the order of the page is actually calculated and assigned to the specific position.
Note: If page repetition is used an exception may appear: A position 2 can contain page no. 1 if each page is supposed to repeat twice.
Also for booklet type impositions, when pages do not exactly fill the whole sheet dragging pages from the Pages for imposition palette may appear broken. If the last page is assigned to a position the scheme is set in such a way that the position contains the last page. If, however, the amount of pages is odd this position will be blank – there is no page that could be placed there.