A system and methods for simultaneous editing of a document by two or more users are disclosed. The document is divided into a number of sections. Each section is stored in a separate data container, which is part of a document tree. A master copy of the document tree is accessible to a server which transmits all or part of the document tree to two or more clients, each of which is operated by a user. The clients can independently lock different sections, allowing the users to simultaneously edit different sections. When a user completes editing a section, the modified section is stored on the master server and broadcast to other users. The document tree is headed by an independently lockable and editable parent container which is used to store summary information and other information, such as default formatting and other document wide information.