Look toward the front of your TCNA Handbook, Fred, page 23 in the 2019 version, under Additional Products Used In Tile Installations. What that's gonna tell you is that there are currently no ASTM, ANSI, or ISO standards for the installation of those Thin Porcelain or Gauged Porcelain Tile Panels. I've been out of touch for a while, but I think that's still the case today.
Perhaps someone else who still attends the national technical committee meetings might be able to provide an update on that.
The usuall tile industry standards for large format tiles would still apply, but the methods and special requirements would be a matter for the tile manufacturers and that's who I'd suggest you contact with your concerns.
From my own experience, which consists entirely of attendance at one manufacturer's (Crossville) training seminar, it ain't your grandfather's tile setting.
