<fw> (forme work) contains a running head (e.g. a header, footer), catchword, or similar material appearing on the current page. [11.6 Headers, Footers, and Similar Matter]
classifies the material encoded according to some useful typology.
Beispielwerte sind etwa: 1] header; 2] footer; 3] pageNum(page number) ; 4] lineNum(line number) ; 5] sig(signature) ; 6] catch(catchword)