Another question: Are temporary expositions covered? I suspect not, but is this spelled out anywhere? Thanks.

Temporary or special exhibitions are not covered by the pass.
http://www.parismuseumpass.fr This is explained on the website. (there is an English version of the site)

Thanks. I wrote Paris Museums Pass and this is the reply:

"The pass gives you access to the museums' permanent collections.
For you to visit the exhibitions you are supposed to purchase a ticket at the museum.
Concerning Versailles, you can see the 'Château', the 'Grand et Petit Trianon'.
There is an extra charge for the State Apartements, for the King's Chamber and for the gardens during the water show."