Some sites have an End User License Agreement (EULA) that stipulates proper use of the site and the data, and cites penalties for misuse. In such cases, you will be required to electronically sign the EULA before logging in the first time. Generally the EULA must be agreed to upon your first login, or when it has been updated.
Administrators
If you are an administrator and need to add or update the EULA, you can ask VAN to update it by sending in a support request.