// build a list of the column numbers which have been edited. You can enhance this to account for errors, etc.
string ls_desc, ls_value, ls_d, ls_prev
integer li_rc
ls_desc = dwo.name + '.ID'
ls_d = describe(ls_desc)
ls_prev = getitemstring(row,'change')
IF IsNull(ls_prev) THEN ls_prev = ''
ls_value = ls_prev + '[' + ls_d + ']' // append new value
li_rc = this.setitem( row, 'change', ls_value)