Forms containing subforms that are set to flow content have a varying number of pages. When the form is rendered, objects are placed inside content areas and, if the data fills the content area, a page break is automatically inserted. By default, all of the pages inherit the format of the default master page.
When more than one master page is available, each one can influence how pages are formatted. In this case, the layout of a master page is applied when the subform that it is associated with is rendered. That is, if the subform is rendered on page 2 of the form, the format of the assigned master page is applied to page 2.
First, you can limit the number of times a master page is used in a form by setting minimum and maximum page-occurrence settings. For example, the first master page needs a minimum and maximum page-occurrence setting of one to indicate that it always occurs only once. For master pages, the default minimum count is 0 and the maximum count is -1. For the second master page, the layout can be rendered on a page an infinite number of times.
Alternatively, you can define the placement of the master pages in the page set, such as in the first printed page, the last printed page, or the printed pages that occur in between. For example, a pay statement has company and employee-specific information on the first page. Subsequent pages show very little company or employee information and a significant amount of time card information. You can define two master pages. The first master page will have the company logo and contact information first, outside the content area. A small content area will follow to receive employee-specific information. The second master page will have a larger content area, possibly covering the whole page, to receive time card information.
By default, all form designs are created with the option of applying master pages by setting minimum and maximum occurrence values. Although different, the result of the rendered page using either option is the same. However, if the form is intended for double-sided printing, use the placement options.
Keep in mind that if you define the placement of the master pages in a form design and then you switch to setting page-occurrence values, you may need to make some changes to the form before it will behave as expected. Also, defining the placement of master pages is recommended only for form designs saved as Acrobat 8 (Static) PDF forms or for form designs intended for printing, including PCL and Postscript.
See also 

Applying master pages to forms whose number of pages vary