Added attributes into <html> of userguide for valid html.
diff --git a/user_guide/installation/downloads.html b/user_guide/installation/downloads.html
index 03ce391..f6561d4 100644
--- a/user_guide/installation/downloads.html
+++ b/user_guide/installation/downloads.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide : Downloading CodeIgniter</title>
diff --git a/user_guide/installation/index.html b/user_guide/installation/index.html
index 89bd256..f01fbb3 100644
--- a/user_guide/installation/index.html
+++ b/user_guide/installation/index.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide : Installation Instructions</title>
diff --git a/user_guide/installation/troubleshooting.html b/user_guide/installation/troubleshooting.html
index 8012261..294ec8a 100644
--- a/user_guide/installation/troubleshooting.html
+++ b/user_guide/installation/troubleshooting.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide : Troubleshooting</title>
diff --git a/user_guide/installation/upgrade_120.html b/user_guide/installation/upgrade_120.html
index 01ffa0a..554a80a 100644
--- a/user_guide/installation/upgrade_120.html
+++ b/user_guide/installation/upgrade_120.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide</title>
diff --git a/user_guide/installation/upgrade_130.html b/user_guide/installation/upgrade_130.html
index 202cc33..95cec49 100644
--- a/user_guide/installation/upgrade_130.html
+++ b/user_guide/installation/upgrade_130.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide</title>
diff --git a/user_guide/installation/upgrade_131.html b/user_guide/installation/upgrade_131.html
index 3219540..dad3e8c 100644
--- a/user_guide/installation/upgrade_131.html
+++ b/user_guide/installation/upgrade_131.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide</title>
diff --git a/user_guide/installation/upgrade_132.html b/user_guide/installation/upgrade_132.html
index 2cf13cc..9a6d075 100644
--- a/user_guide/installation/upgrade_132.html
+++ b/user_guide/installation/upgrade_132.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide</title>
diff --git a/user_guide/installation/upgrade_133.html b/user_guide/installation/upgrade_133.html
index 9bd50ac..b71694c 100644
--- a/user_guide/installation/upgrade_133.html
+++ b/user_guide/installation/upgrade_133.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide</title>
diff --git a/user_guide/installation/upgrade_140.html b/user_guide/installation/upgrade_140.html
index 6ee915f..e03547b 100644
--- a/user_guide/installation/upgrade_140.html
+++ b/user_guide/installation/upgrade_140.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide</title>
diff --git a/user_guide/installation/upgrade_141.html b/user_guide/installation/upgrade_141.html
index 90bb62a..239fa51 100644
--- a/user_guide/installation/upgrade_141.html
+++ b/user_guide/installation/upgrade_141.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide</title>
diff --git a/user_guide/installation/upgrade_150.html b/user_guide/installation/upgrade_150.html
index a6c93e8..456e4da 100644
--- a/user_guide/installation/upgrade_150.html
+++ b/user_guide/installation/upgrade_150.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide</title>
diff --git a/user_guide/installation/upgrade_152.html b/user_guide/installation/upgrade_152.html
index d0a19ba..370e3b8 100644
--- a/user_guide/installation/upgrade_152.html
+++ b/user_guide/installation/upgrade_152.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide</title>
diff --git a/user_guide/installation/upgrade_153.html b/user_guide/installation/upgrade_153.html
index 5671b48..33d3837 100644
--- a/user_guide/installation/upgrade_153.html
+++ b/user_guide/installation/upgrade_153.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide</title>
diff --git a/user_guide/installation/upgrade_154.html b/user_guide/installation/upgrade_154.html
index 07dfa5d..6e8316c 100644
--- a/user_guide/installation/upgrade_154.html
+++ b/user_guide/installation/upgrade_154.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide : Upgrading from 1.5.3 to 1.5.4</title>
diff --git a/user_guide/installation/upgrade_160.html b/user_guide/installation/upgrade_160.html
index dffbb76..231404d 100644
--- a/user_guide/installation/upgrade_160.html
+++ b/user_guide/installation/upgrade_160.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide : Upgrading from 1.5.3 to 1.5.4</title>
diff --git a/user_guide/installation/upgrade_b11.html b/user_guide/installation/upgrade_b11.html
index 09e93c0..1f47418 100644
--- a/user_guide/installation/upgrade_b11.html
+++ b/user_guide/installation/upgrade_b11.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide</title>
diff --git a/user_guide/installation/upgrading.html b/user_guide/installation/upgrading.html
index fccebe0..c40da5a 100644
--- a/user_guide/installation/upgrading.html
+++ b/user_guide/installation/upgrading.html
@@ -1,5 +1,5 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>CodeIgniter User Guide : Upgrading From a Previous Version</title>