[quote user="Bruce Reeves SRNS"]
If you look at "msmesh.h", you'll see this note:
All mdlMesh functions are deprecated. It is strongly recommended that code PolyfaceHeaders be used in their place.
[/quote]
While your observation is correct, that comment didn't make it into the documentation. Well spotted!
But, should we really be in the position where it's necessary to read the header files to find what is missing in the help file? Surely the automated document generation should take care of that? Furthermore, the recommendation is inaccurate: there is no PolyfaceHeaders (plural) class. There is a PolyfaceHeader (singular) class, which you'll find in header file include\Geom\Polyface.h.
Historically, MDL developers have been well-known for chewing iron filings for breakfast. Advances in programming language sophistication don't seem to be ameliorating our dietary habits.