erasable_chars.append('0')
 
             erased = ''
 ####            dbg("fstr[0]:'%s'" % fstr[0])
 ####            dbg('field_index:', field._index)
 ####            dbg("fstr[0] in erasable_chars?", fstr[0] in erasable_chars)
                 erasable_chars.append('0')
 
             erased = ''
 ####            dbg("fstr[0]:'%s'" % fstr[0])
 ####            dbg('field_index:', field._index)
 ####            dbg("fstr[0] in erasable_chars?", fstr[0] in erasable_chars)