BuzzStream allows you set a custom field as Project Specific in People or Link Partners (Media Outlets) at the time the custom field is created. Links do not have project specific custom fields as each custom field for a link is individual to that link in that project.
Relationship stage is an example of a custom field that is project specific (if projects are enabled).
For example I have two projects. Link Partner domain.com is in both projects. In Project 1 domain.com has a link that is linking and the Relationship Stage is set to Link Accepted. In Project 2 domain.com is a prospect and the Relationship stage is project specific.
Another example of a project specific field is a custom field labeled Source. Let's say I use Source to track which tool I used to find a link Prospect. Let's say I use multiple tools for prospecting. These tools might include Google Searches, Majestic SEO, Opensiteexplorer.org, and Citation Labs Link Prospecting tool. Lats take thedomain.com as our example. thedomain.com is in 4 projects. It was returned as a prospect from all 4 tools sets for different projects. I added the Link Partner to each project using the import tools in BuzzStream. In my import I included a value for the custom field so I could track what tool the Link Partner was sourced from. Here's a detail of the project and the source value for thedomain.com:
|3||Citation Labs Link Prospecting tool|