[PW] Any such creature?

[dhesson1]

Hello Fellow Womb at s!
    I received this question from a friend and I tried to google but I am
not sure how to pose the question so I was wondering if anyone can point me
in the right direction.  The question is:

"I know that there is a list of what I can only refer to as "referenced"
operatic roles out there some place.  These are names of individuals that
are referenced in an opera but are never seen and of course, never heard.
(It's like talking about Mrs. Santa Claus.  Nobody ever sees or hears her.)
Have you ever seen it?  I think I saw it in reference to someone's fake
resume'  He listed all of these roles as his great performances to see if
anyone actually read or knew these things."

If anyone knows the answer to this question I will be very grateful and my
friend will be quite impressed!

Many thanks!
Donna Hesson
dhesson at jhmi.edu