expands to "ld"/"lu", respectively since off_t is a long (not an int):
examples:
ftpsrvr.c:1374:77: warning: format '%d' expects argument of type 'int', but argument 6 has type 'off_t {aka long int}' [-Wformat=]
   lprintf(LOG_WARNING, "%04d <%s> !DATA cannot send file (%s) with size of %"PRIdOFF" bytes"
websrvr.c:6063:45: warning: format '%u' expects argument of type 'unsigned int', but argument 5 has type 'off_t {aka long int}' [-Wformat=]
   lprintf(LOG_INFO,"%04d Sending file: %s (%"PRIuOFF" bytes)"