acquiring row and page level locks - Mailing list pgsql-general

hi ,
coudl some one tell me how to acquire row-level and page level locks in
postgresql.
iam aware that table level locks can be acquired by the command:
"lock table *tablename* in *locktype* mode;
thanks

_________________________________________________________________
Enter for your chance to IM with Bon Jovi, Seal, Bow Wow, or Mary J Blige
using MSN Messenger http://entertainment.msn.com/imastar