From http://www.w3schools.com (Copyright Refsnes Data)
XSL-FO pages are filled with data from <fo:flow> elements.
XSL-FO uses <fo:page-sequence> elements to define output pages.
Each output page refers to a page master which defines the layout.
Each output page has a <fo:flow> element defining the output.
Each output page is printed (or displayed) in sequence.
XSL-FO pages are filled with content from the <fo:flow> element.
The <fo:flow> element contains all the elements to be printed to the page.
When the page is full, the same page master will be used over (and over) again until all the text is printed.
The <fo:flow> element has a "flow-name" attribute.
The value of the flow-name attribute defines where the content of the <fo:flow> element will go.
The legal values are:
From http://www.w3schools.com (Copyright Refsnes Data)