Go here:
http://www.monierlifetile.com/techni...l_GuideWEB.pdf
For System Two, Mechanically Attached Tile,
- page 52 of 178 under A. Standard Roll Valley, 2. Open Valley, it talks about pointing up the open areas with mortar.
(I'll add more with edit as I find them.)
- page 54 of 178 under 3.14 B. Mortar Finish, it talks about pointing up along the rake/gable tile with mortar.
- page 54 of 178 under 3.15 Wall abutments, it talks about pointing up as being optional - this is not specific as to whether or not this is referring to tile running parallel with an abutting wall, had a head wall, or where the tile dies into a wall, but it does limit the space to approximately 1/2". I guess it also applies to head wall abutments as it does contain that note about not nailing through those flashings, i.e., using roof tile adhesive there.