Role sets the optional parameter "role": User access types for blogs to include in the results, e.g. AUTHOR will return blogs where the user has author level access. If no roles are specified, defaults to ADMIN and AUTHOR roles.
"ADMIN" - Admin role - Blogs where the user has Admin level access. "AUTHOR" - Author role - Blogs where the user has Author level
"READER" - Reader role - Blogs where the user has Reader level
access (to a private blog).