Teresa S --
From your question, it sounds like you are using Project Server 2007. If
so, in the future please specify your Project Server version in each
question, as it helps us to answer your questions correctly.
Assuming you are using Project Server 2007, there is a standard Project
field called Project Type. If you add it to a Project Center view, the
field reveals whether each project in the Project Center is a regular
project (called Project), a Master Project, an Inserted Project (part of a
master project), or a Maintenance Project. Both published Proposals and
Activity plans are designated as Maintenance Projects.
You can use this field to identify project types, but you cannot filter on
this field in the definition of a Project Center view, as it triggers an
error in the Project Center view and causes the system to display NO
projects at all. I have reported this as another bug in Project Server
2007. Hope this helps.