Can several people work on the plan at the same time?
It can be done, but it is only recommended with reservations, due to the high risk that one person will over-write the work of another.
Web applications work via requests. You send a request to a web page to view it, then you fill out a form and send another request to submit that information to the server and get back a response. The web is stateless, which means one request does not know anything about previous or future requests made by you or any other user. We have also implemented an auto-save feature in our application - when you click the "Next" or "Previous" buttons, for instance, the application automatically saves your page - which complicates matters further.
So what can possibly happen goes like this:
We have implemented some features and steps you can take to help to prevent accidental over-writes.