Ref

official documentation found here: https://developers.facebook.com/docs/games/services/measurement#referraltracking https://developers.facebook.com/docs/sharing/opengraph/using-actions#linkreferer

When people go to your application via a link in Facebook, it should contain a fb_source GET variable that will indicate where the person clicked the link. If fb_source is not present, an older ref parameter with similar values may be present. The values aren't always completely clear so here is a table of the possible values and their meanings:

fb_source value	ref value	Meaning	Description
aggregation		aggregation	clicked on an item in an Open Graph aggregation
appcenter		App Center	Came to your application through the new App Center
appcenter_request		App Center request	Came to your application through a request in the App Center Requests
bookmark_apps	bookmarks	bookmark	On the "Home" page of Facebook the user clicked the bookmark for your application that appears in the far left column.
bookmark_favorites	bookmarks	bookmark	The user clicked on the bookmark to your application after earlier moving it to their list of favorite applications.
bookmark_seeall	bookmarks	bookmark	Person clicked "more" on the apps menu and then entered the application from http://www.facebook.com/bookmarks/apps
canvas_bkmk_top canvasbookmark		canvas bookmark (top)	When in an application, there are a few bookmarks shown along the right above the Facebook ads (currently 3 links to applications and a "more" to see more applications). You'll see this fb_source value if the person came to your application from one of those links above the "more" link.
canvas_bkmk_more canvasbookmark_more		canvas bookmark (more)	When in an application, there are a few bookmarks shown along the right above the Facebook ads (currently 3 links to applications and a "more" to see more applications). You'll see this fb_source if your application was clicked as a link below the "more" divider.
canvasbookmark_recommended		canvas bookmark (recommended)	link below the canvas bookmarks showing applications that Facebook recommends
dashboard_bookmark		dashboard bookmark	List of apps and games at top of the "dashboard" page ( http://www.facebook.com/games or http://www.facebook.com/?sk=apps )
dashboard_toplist		dashboard top list	List of games at bottom of the requests page ( http://www.facebook.com/games or http://www.facebook.com/?sk=apps )
dialog_permission
ego	games_featured featured_game	featured game	On the Games or Apps and Games page there is a list of "featured games" in the right column, the user clicked one of these links.
feed nf		news feed	The user came to your application by clicking a link on a news feed item.
feed_achievement
feed_highscore
feed_music
feed_opengraph		news feed open graph story	The user came to your application by clicking an Open Graph story in their news feed.
feed_passing
feed_playing
feed_video
games_my_recent		Games page: Your Games	On the Games page there is a section titled "Your Games" that show the 5 most recently played games. The user clicked one of these links.
games_friends_apps		Games page: Friends' Games	At the very bottom of the Games page there is a section titled "Friends' Games" that shows several friends and 1-3 applications they've used. The user clicked one of these links.
hovercard			small pop-over describing the app that you see when you mouse-over the name of the application on a newsfeed post
message
mf		minifeed	saw this tag on an image news feed item, but not sure what it is Wong 17:20, 7 February 2011 (UTC)
notification	notif	notification	clicked on a notification (these appear in the drop down when you click the planet in the top bar or at http://www.facebook.com/notifications.php )
other_multiline			The user came from the "<User> played <app>" feed on the canvas page.
pymk		People You May Know	not likely to be seen in a third party application, but it's a fb_source value that appeared on the Home page under "People You May Know"
recent_activity		Recent Activity	clicked on an Open Graph action in the "Recent Activity" section of the timeline
reminders			application request reminders that are shown on the Home page at the top right
request		request	person replied to Facebook request or clicked the link to your app from a request on the request page
search	ts	top search	If a user starts typing in a search and then selects one of the suggestions that pop up below the top search box, the fb_source will have a value of "ts"
ticker		ticker	clicked on an Open Graph action in the Ticker
timeline		timeline
timeline_og		timeline open graph	clicked on the app name or open graph object name in a timeline post
timeline_news
timeline_passing
timeline_recent	rua		"Apps - recently used" link on person's profile timeline

Codes no longer used

fb_source value	ref value	Meaning	Description
appd		Application Directory	Someone came from the infrequently used Application Directory
appd_friends_apps		Apps page: Friends' Apps	At the very bottom of the Apps page there is a section titled "Friends' Apps" that shows several friends and 1-3 application they've used. The user clicked one of these links.
appd_my_recent		Apps page: Your Apps	On the Apps page there is a section titled "Your Apps" that show the 5 most recently used applications. The user clicked one of these links.