There are several futures that can help to get the information. The best place to get token source is click "Browse available Tokens". Here are some examples.
Q: By default, Yale user can log into Drupal with their netid, Drupal will create an account with some basic from Yale Directory, so if a user log into a form, we can get user's information as default value with the following token:
- [current-user:name] for Current login user's name
- [current-user:mail] for E-mail