Use the \note and \warning macros where appropriate.
diff --git a/Doc/lib/librexec.tex b/Doc/lib/librexec.tex
index d5e2d02..6184a48 100644
--- a/Doc/lib/librexec.tex
+++ b/Doc/lib/librexec.tex
@@ -15,10 +15,10 @@
 only have access to modules and functions that are deemed safe; you
 can subclass \class{RExec} to add or remove capabilities as desired.
 
-\emph{Note:} The \class{RExec} class can prevent code from performing
+\note{The \class{RExec} class can prevent code from performing
 unsafe operations like reading or writing disk files, or using TCP/IP
 sockets.  However, it does not protect against code using extremely
-large amounts of memory or processor time.  
+large amounts of memory or processor time.}
 
 \begin{classdesc}{RExec}{\optional{hooks\optional{, verbose}}}
 Returns an instance of the \class{RExec} class.