Locking Records of Certain Users (don't allow Update Record)

Hi everyone,

I have a problem about locking records.

Multiple users can login to my database and perform updates to records. However,
I do not want them to update (but allowing to view the records) certain records
(meaning they originally created the record). I put in place a user-level security
and each user is assigned to different permission groups.

I'm just wondering if it is possible to do this.

Thanks in advance!

PC