This is borrowed from the Official CBCS Signature Programs page on Facebook. While it will be kept up to date as best as possible, everyone is encouraged to visit the page and check the pinned post for updates.

Originally Posted by Mark Roman
Latest Updated List of Signature restrictions: AWs CANNOT self-witness ROBERT KIRKMAN, TODD MCFARLANE, ADAM HUGHES (only through Trinity Comics private signing), J. SCOTT CAMPBELL (only through CBCS scheduled & private signings), STAN LEE (only thru Excelsior Collectibles Steve McDonald, Jeff Avigliano, Genuine COA & Trinity Comics private signing), JIM LEE (only thru CBCS & Trinity Comics private signing), JIM STARLIN (only thru a CBCS witness or an AW working the CBCS booth) & FRANK MILLER (only through Trinity Comics private signing). ALL signatures qualify for the VSP (red label). **CBCS announced private signings could simply be dropped off at the CBCS booth of that particular convention the comic book creators will be signing at.**

***NEW*** Scott Snyder, Tom King, Jock, Steve Orlando, Joshua Williamson, Marguerite Bennett & Greg Capullo can only qualify for yellow label (ASP) if you have a CBCS form, to have handler/rep. Doug Peter's or a CBCS representative's initials on the form, which will show proof that you paid for the signature that will ultimately be certified. CBCS will discontinue private signings with the Comic Sketch Art group above. CBCS AW witnessing is still allowed.. ***

* Some of the artists & writers will have a ticket process OR initials on the CBCS submission forms by the art rep or managers, to qualify for CBCS yellow label (ASP) ONLY. LARRY LIEBER, JOE GIELLA, JOHN ROMITA JR. & TONY MOORE will work this way, by that comic book creator's handlers (Desert Wind Comics, Jeff Harnett & Mr. & Mrs. Tony Moore). Tickets that are not given to CBCS or no initials on the CBCS submission forms by the art reps or managers, will not qualify as ASP & will be given the option for a red label (VSP).*

Official CBCS Signature Programs Facebook page