The DITA specification does not encompass the notion of a table footer row. However, you can assign an @outputclass value to the <row> and <strow> elements generated from your FrameMaker table footer rows, to maintain that information.
To assign an @outputclass to footer rows:
; UseTableFooterClass = No (default, treat footer rows as
; body rows), or Yes (use body element but set outputclass)
; TableFooterClass = @outputclass to use for footer rows,
When UseTableFooterClass=Yes, each footer row of every FrameMaker table becomes a DITA <row> or <strow> element that includes an @outputclass attribute with the value assigned to TableFooterClass. The default is @outputclass="footer".
When UseTableFooterClass=No, footer rows become table body rows in DITA output.