Upper "S" in chmod !!!

From: Raul Sossa S. <RSossa_at_datadec.co.cr>
Date: Tue, 10 Apr 2001 16:25:25 -0600

Hello guys!!
Who can explain me what does this upper "S" mean
in the following chmod sequence, doesn't it have to be lowercase???
------------------------------------------------------------------------
# touch x
# chmod -u+s x
# ls -al x
---S--S--- 1 root system 0 Apr 10 10:19 x
# chmod 640 x
# ls -al x
-rw-r----- 1 root system 0 Apr 10 10:19 x
# chmod u+s x
# ls -al x
-rwSr----- 1 root system 0 Apr 10 10:19 x
------------------------------------------------------------------------

Thanks!
Received on Tue Apr 10 2001 - 22:23:40 NZST