Using Redgate Reflector tool, what does it mean when some class names are light grey? -

i'm using reflector , can see class names black , others light grey.

i tried doing search means , not find user guide or indicate means.

i'm wondering if might related public/private of class? i'm assuming envelope means sealed.

the black public , gray not public (so internal, private, etc.).

if go tools menu -> options , choose browser item, can change visibility dropdown show "public items only". click ok, gray items hidden.