Lays down the subform set at the top of the page, whenever the specified page is rendered (introduces a page break if one does not occur naturally).
Places the subform set at the top of the odd page whenever the specified page is rendered (introduces a page break if one does not occur naturally).
Places the subform set at the top of the even page whenever the specified page is rendered (introduces a page break if one does not occur naturally).
See also 

Subform set properties in the Pagination tab