When you set the database property "Allow document locking," users with Author access or higher can lock documents in that database. Locking a document prevents editing and replication conflicts by ensuring that person who locks the document has exclusive rights to modify the document; others with the same rights cannot modify a locked document even if they are working on a different replica on the same LAN. Managers of a database cannot edit a locked document. However, managers can unlock documents that are locked.
For information on how users lock a document, see Locking Documents in Lotus Notes Help. Or, go to http://www.lotus.com/ldd/doc to download or view Lotus Notes Help.