added docs for Output class property
diff --git a/user_guide/libraries/output.html b/user_guide/libraries/output.html
index 70f0c1f..4110480 100644
--- a/user_guide/libraries/output.html
+++ b/user_guide/libraries/output.html
@@ -137,6 +137,12 @@
<h2>$this->output->cache();</h2>
<p>The CodeIgniter output library also controls caching. For more information, please see the <a href="../general/caching.html">caching documentation</a>.</p>
+<h2>Parsing Execution Variables</h2>
+
+ <p>CodeIgniter will parse the pseudo-variables <var>{elapsed_time}</var> and <var>{memory_usage}</var> in your output by default. To disable this, set the <var>$parse_exec_vars</var> class property to <var>FALSE</var> in your controller.
+
+ <code>$this->output->parse_exec_vars = FALSE;</code>
+
</div>
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