Flow objects are called that because the text in them “flows” and is arranged to fit the page by the displaying software. The content of a page is handled with flow objects.
There are two kinds of flow objects: fo:static-content and fo:flow. A fo:static-content flow object holds content, such as the text that goes into headers and footers that are repeated on the pages of the page sequence. The fo:flow flow object, on the other hand, holds the text itself that makes up the content of the document. The following fo:flow object has a single property: flow-name.