I'm rewording the PMS sections on dependencies to avoid permitting
overly lax circular dependency resolution. Which of these wordings is
accurate, given that usable means "has its RDEPENDs installed and
usable"?

1. During pkg_preinst and pkg_postinst, any package dependency that is
in both DEPEND and RDEPEND must be installed and usable.

2. During pkg_preinst and pkg_postinst, at least one of the following
conditions must be met:
  a. every package dependency in DEPEND must be installed and usable
  b. every package dependency in RDEPEND must be installed and usable

Do not attempt to write on both sides of the paper at once.

-- 
Ciaran McCreesh