diff -r 10bc73197a57 -r fc458f304f93 src/Doc/System/Basics.thy
--- a/src/Doc/System/Basics.thy	Fri May 17 18:50:55 2013 +0200
+++ b/src/Doc/System/Basics.thy	Fri May 17 19:04:52 2013 +0200
@@ -379,6 +379,7 @@
     -W IN:OUT    startup process wrapper, with input/output fifos
     -e MLTEXT    pass MLTEXT to the ML session
     -m MODE      add print mode for output
+    -o OPTION    override Isabelle system OPTION (via NAME=VAL or NAME)
     -q           non-interactive session
     -r           open heap file read-only
     -w           reset write permissions on OUTPUT
@@ -438,6 +439,9 @@
   option inhibits interaction, thus providing a pure batch mode
   facility.
 
+  \medskip Option @{verbatim "-s"} allows to override Isabelle system
+  options for this process, see also \secref{sec:system-options}.
+
   \medskip The @{verbatim "-I"} option makes Isabelle enter Isar
   interaction mode on startup, instead of the primitive ML top-level.
   The @{verbatim "-P"} option configures the top-level loop for