Hi Paul, If you are interested in parameterizations of time walk corrections, you can take a look at the CLAS note http://www.jlab.org/Hall-B/notes/clas_notes02/02-007.pdf Cheers, Elton. -- Elton Smith Jefferson Lab MS 12H5 12000 Jefferson Ave Suite #16 Newport News, VA 23606 (757) 269-7625 (757) 269-6331 fax