Many small edits.
diff --git a/man/man3/exec.3 b/man/man3/exec.3
index 2c5b166..1a0a8a8 100644
--- a/man/man3/exec.3
+++ b/man/man3/exec.3
@@ -128,3 +128,14 @@
 This is a clumsy way to deal with Unix's lack of
 a union directory for
 .BR /bin .
+.PP
+To avoid name conflicts with the underlying system,
+.I exec
+and
+.I execl
+are preprocessor macros defined as
+.I p9exec
+and
+.IR p9execl ;
+see
+.IR intro (3).