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+If you want to build ns3, you need to install scons (see
+http://www.scons.org). scons takes care of building
+the whole source tree using your system compiler. scons
+0.91.1 and 0.91.96 have been tested and are known to 
+work on linux FC5, Mac os X and MinGW.
+
+To start a build, you can just type 'scons' which
+will generate a debug shared build by default, located
+in the directory 'build-dir/dbg-shared/bin' and
+'build-dir/dbg-shared/lib'.
+
+1) Options
+----------
+
+- verbose: if you have install scons 0.91.96, the default
+  build output is terse. To get a more verbose output, you
+  need to set the 'verbose' variable to 'y'.
+
+Example:
+scons verbose=y
+
+2) Targets
+----------
+
+- dbg-shared: a debug build using shared libraries.
+  The files are built in 'build-dir/dbg-shared/'.
+Example:
+scons dbg-shared
+
+- dbg-static: a debug build using static libraries
+  The files are built in 'build-dir/dbg-static/'.
+Example:
+scons dbg-static
+
+- opt-shared: an optimized build using shared libraries.
+  The files are built in 'build-dir/opt-shared/'.
+Example:
+scons opt-shared
+
+- opt-static: an optimized build using static libraries.
+  The files are built in 'build-dir/opt-static/'.
+Example:
+scons opt-static
+
+- dbg: an alias for dbg-shared
+Example:
+scons dbg
+
+- opt: an alias for opt-shared
+Example:
+scons opt
+
+- all: alias for dbg-shared, dbg-static, opt-shared 
+  and opt-static
+Example:
+scons all
+
+- dist: generate a release tarball and zipfile from the 
+  source tree. The tarball and zipfile name are generated
+  according to the version number stored in the SConstruct
+  file.
+Example in SConstruct:
+ns3 = Ns3 ()
+ns3.name = 'foo'
+ns3.version = '0.0.10'
+Example command:
+scons dist
+Example output:
+foo-0.0.10.tar.gz
+foo-0.0.10.zip
+
+- distcheck: generate a release tarball and zipfile and 
+  attempt to run the 'all' target for the release tarball.
+Example:
+scons distcheck