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+# Flatten Subsystem Tool
+
+The Flatten Subsystem tool automatically flattens a Simulink subsystem, that
+is, it moves the subsystem contents up one level, reconnects the signals, and
+removes the subsystem block. This tool is useful for making quick transformations
+to a model by automating the tedious task of manually copying and connecting
+the many elements contained in a subsystem.
+
+*Note: This functionality has been since included in Matlab/Simulink 2014a
+as the "Expand Subsystem" operation. This tool is still beneficial for earlier
+versions of Matlab/Simulink, as well as handling more types of subsystems*
+
+## User Guide
+For installation and other information, please see the [User Guide](doc/FlattenSubsystem_UserGuide.pdf).