Mary Smith wants to use the workstations at HPC@UNM. She is a post-doc sponsored by Marc Wilson. Marc already runs projects at the Center, and so he is listed as the Principal Investigator. In particular, he is the PI of project 2003123. When Mary goes to the Account request page, she specifies Project 2003123 when she asks for an Account. She also specifies her contact information, her preferred login name, and that she wants to use the workstations. Marc will be contacted to verify that Mary should be a member of this Project.
Later, Mary needs to use LosLobos, still on Marc's project. She therefore requests a new Account, using the same login name and Project, but a different Machine.
Still later, Mary originates a brand new line of research. She and Marc agree that she should be the PI on that project. So an new Project gets requested, with Mary as the PI. Once the project is created, new Accounts can be added to it. As PI, Mary now receives regular reports about all usage billed to her project. She also gets asked to verify requests to add Accounts to her Project, and to prune Accounts from her Project as necessary.
For starters, everyone has a 'default Project' that gets billed if you don't do anything special. If you are working on multiple projects, you can bill a Project directly (as long as you are authorized to do so). When you submit a job, use the '-A' flag with the project number of the project you wish to bill. So if Mary wants to bill Marc's project directly, she would use the command:
qsub ... -A 2003123 ...