/usr/lib or /usr/libexec?

[Toralf Lund <toralf procaptura com>]

OK, I know this is somewhat off-topic, but it seems to me that people 
who read this will be the most likely to have an answer for my questions:

I'm creating a package containing a number of DSOs that are considered 
internal to the package, so I don't want to install them directly on 
/usr/lib, but rather use a package specific directory also linked into 
the RPATH or RUNPATH of my programs. Where should I install this 
directory? There seem to be two alternatives:

  1. /usr/lib/<package>
  2. /usr/libexec/<package>

Which would be the right one to use? And what if I include "internal" 
executables, too? Should these go in lib or libexec?

BTW, as far as I can tell, the FHS doesn't even mention libexec. Or 
should I interpret it as one case of "Alternate format libraries" as 
described in section 4.8?

- Toralf