P3914R0: Re NB US 263-396 (C++26 CD).

Fixes NB US 263-396 (C++26 CD).

Author: eisenwave

source/exec.tex

@@ -8532,8 +8532,13 @@
 
 \pnum
 \returns
-A non-null shared pointer to an object
-that implements the \tcode{parallel_scheduler_backend} interface.
+An object \tcode{p},
+such that \tcode{p.get()} points to a \tcode{parallel_scheduler_backend} object
+that is a base-class subobject
+of some most derived object \tcode{o} within its lifetime.
+The lifetime of \tcode{o} does not end
+as long as there exists a \tcode{shared_ptr} object \tcode{q} within its lifetime
+such that \tcode{q.owner_equal(p)} is \tcode{true}.
 
 \pnum
 \remarks