Added example of how to test using lower bits of a long provider.
diff --git a/commons-rng-examples/examples-stress/stress_test.md b/commons-rng-examples/examples-stress/stress_test.md
index e6eee70..dbb0d90 100644
--- a/commons-rng-examples/examples-stress/stress_test.md
+++ b/commons-rng-examples/examples-stress/stress_test.md
@@ -74,8 +74,8 @@
Test platform Endianness
------------------------
-The stress test application will output raw binary data for generated integers. An integer is 4
-bytes and thus the byte order or [Endianness](https://en.wikipedia.org/wiki/Endianness) of the data
+The stress test application will output raw binary data for generated integers or longs.
+An integer is 4 bytes and a long is 8 bytes and thus the byte order or [Endianness](https://en.wikipedia.org/wiki/Endianness) of the data
must be correct for the test application. The stress test application can support either big-endian
or little-endian format. The application will auto-detect the platform and will default to output
binary data using the native byte order.
@@ -144,6 +144,35 @@
> java -jar target/examples-stress.jar results \
target/tu_* \
- target/dh_* --ignore-sums
+ target/dh_*
Various formats are available. Use the `--help` option to show the available options.
+
+Test 64-bit generators
+----------------------
+
+The available random generators output either 32-bits or 64-bits per cycle. The test applications
+**Dieharder** and **TestU01** require 32-bit input. The standard method for a 64-bit generator is
+to use the upper and then lower 32-bits of each 64-bit output. The stress test application has
+options to use only the upper or the lower 32-bits for testing. These can then be bit-reversed or
+byte-reversed if desired.
+
+The `list` command can output available generators by provider type. For example to output the
+64-bit providers to a `rng64.list` file:
+
+ > java -jar target/examples-stress.jar list \
+ --provider long > rng64.list
+
+The list can then be used to test 64-bit providers, for example to test the lower 32-bits in reverse
+order using **BigCrush**:
+
+ > java -jar target/examples-stress.jar stress \
+ --list rng64.list \
+ --low-bits \
+ --reverse-bits \
+ --prefix target/tu_lo_r_ \
+ ./stdin2testu01 \
+ BigCrush
+
+If a 32-bit provider is used with the `--low-bits` or `--upper-bits` options then an error
+message is shown.
