even smarter setup for several installations of Poly/ML 3.x and 4.0;

--- a/etc/settings	Thu Oct 12 17:39:47 2000 +0200
+++ b/etc/settings	Thu Oct 12 17:47:32 2000 +0200
@@ -14,17 +14,27 @@
 # binaries.  Do not invent new ML system names unless you know what
 # you are doing.  Only one of the sections below should be activated.
 
-# Poly/ML 3.x or later
-POLYML_HOME=$(choosefrom \
-  "$ISABELLE_HOME/contrib/polyml" \
-  "$ISABELLE_HOME/../polyml" \
-  "/usr/share/polyml" \
-  "/usr/local/polyml" \
-  "/opt/polyml")
-ML_SYSTEM=$("$POLYML_HOME/bin/polyml-version" 2>/dev/null || echo polyml)
-ML_PLATFORM=$("$POLYML_HOME/bin/polyml-platform" 2>/dev/null)
-ML_HOME="$POLYML_HOME/$ML_PLATFORM"
-ML_OPTIONS="-h 30000"
+# Poly/ML 3.x and 4.0
+if [ -e /usr/bin/poly -a -e /usr/lib/poly ]; then
+  #maybe a shrink-wrapped polyml-4.0 on x86-linux ...
+  ML_SYSTEM=polyml-4.0
+  ML_PLATFORM=x86-linux
+  ML_HOME=/usr/bin
+  ML_DBASE=/usr/lib/poly/ML_dbase
+  ML_OPTIONS="-h 30000"
+else
+  #... or rather a self-contained multi-platform installation
+  POLYML_HOME=$(choosefrom \
+    "$ISABELLE_HOME/contrib/polyml" \
+    "$ISABELLE_HOME/../polyml" \
+    "/usr/share/polyml" \
+    "/usr/local/polyml" \
+    "/opt/polyml")
+  ML_SYSTEM=$("$POLYML_HOME/bin/polyml-version" 2>/dev/null || echo polyml)
+  ML_PLATFORM=$("$POLYML_HOME/bin/polyml-platform" 2>/dev/null || echo platform)
+  ML_HOME="$POLYML_HOME/$ML_PLATFORM"
+  ML_OPTIONS="-h 30000"
+fi
 
 # Standard ML of New Jersey 110 or later
 #ML_SYSTEM=smlnj-110